Anti-pathogenic methods

ABSTRACT

The present disclosure teaches the protection of plants and human and non-human subjects from pathogens. The present disclosure enables a multivalent approach to inhibiting pathogen infection in plant and human and non-human animal subjects and to ameliorate damage to susceptible subjects.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage of International ApplicationNo. PCT/AU2013/001346, filed Nov. 22, 2013, which claims the benefit ofU.S. Provisional Patent Application No. 61/729,467, filed Nov. 23, 2012;both of which are hereby incorporated by reference to the extent notinconsistent with the disclosure herewith.

FILING DATA

This application is associated with and claims priority from U.S.Provisional Application No. 61/729,467, filed on 23 Nov. 2012, entitled“Anti-pathogenic methods”, the entire contents of which, areincorporated herein by reference.

FIELD

The present disclosure teaches the protection of plants and human andnon-human subjects from pathogens. The present disclosure enables amultivalent approach to inhibiting pathogen infection in plant and humanand non-human animal subjects and to ameliorate damage to susceptiblesubjects.

BACKGROUND

Bibliographic details of the publications referred to by author in thisspecification are collected alphabetically at the end of thedescription.

Reference to any prior art in this specification is not, and should notbe taken as, an acknowledgment or any form of suggestion that this priorart forms part of the common general knowledge in any country.

Crop losses due to infection by plant pathogens (phytopathogens) such asfungal and insect pathogens are a major problem in the agriculturalindustry and each year, millions of dollars are spent on the applicationof fungicides to curb these losses (Oerke and Dehne (2004) CropProtection 23:275-285). There is a need to identify newanti-phytopathogen strategies. This is particularly important given thepropensity for pathogens to develop resistance. Fungal infection ofhuman and non-human subjects can also lead to significant discomfort andmajor health issues. Pathogenic fungi are also a serious concern forhuman health and for the economy. Human fungal pathogens causelife-threatening hospital-acquired diseases with high mortality rates aswell as less severe superficial infections.

Plants have evolved to produce peptides to protect against pathogens.Their specificity is likely influenced by the evolutionary in responseto exposure to various pathogens.

Plant defensins represent one type of anti-pathogen molecule. There is awide variety of defensins with differing spatial and temporal patternsof expression and spectra of activity. Generally, plant defensins aredivided into two major classes. Class I defensins consist of anendoplasmic reticulum (ER) sequence followed by a mature defensindomain. Class II defensins are produced as larger precursors withC-terminal pro-domains or pro-peptides (CTPPs) of about 33 amino acidsin addition to the ER signal sequence and mature domain.

The mechanism underlying the specificity of these peptides is yet to befully elucidated, although interactions with plasma membrane componentsare presumed to be involved. Since membrane permeabilization is a commonactivity of many anti-pathogen peptides and the membrane composition ofvarious cell types is highly variable, the presence of specific lipidsis postulated in some cases to be responsible for the efficacy ofanti-pathogen peptides.

Plant pathogens induce significant plant yield loss and currentstrategies for pathogen control are both expensive and potentiallydamaging to the environment. Given the need to improve the economy ofagriculture production, new strategies are required for protectingagronomic and ornamentally important plants from a range of diseases,especially fungal disease. Pathogenic fungi are also a serious concernfor human health and for the economy. Current therapies require longtreatment regimes and patients often suffer from associated livertoxicity. Resistance to current therapies is also developing creating aneed for novel therapeutics.

SUMMARY

Throughout this specification, unless the context requires otherwise,the word “comprise” or variations such as “comprises” or “comprising”,will be understood to imply the inclusion of a stated element or integeror method step or group of elements or integers or method steps but notthe exclusion of any element or integer or method step or group ofelements or integers or method steps.

As used in the subject specification, the singular forms “a”, “an” and“the” include singular and plural aspects unless the context clearlydictates otherwise. Thus, for example, reference to “a permeabilizingdefensin” includes a single permeabilizing defensin, as well as two ormore permeabilizing defensins; reference to “an agent” includes a singleagent, as well as two or more agents; reference to “the invention”includes a single or multiple aspects taught by the disclosure. Aspectsdisclosed herein are encompassed by the term “invention”. All aspects ofthe invention are enabled within the width of the claims.

Nucleotide and amino acid sequences are referred to by a sequenceidentifier number (SEQ ID NO). The SEQ ID NOs correspond numerically, tothe sequence identifiers <400>1 (SEQ ID NO:1), <400>2 (SEQ ID NO:2),etc. A summary of sequence identifiers is provided in Table 1.

Disclosed herein is a method for reducing damage to crops and ornamentalplants caused by pathogens such as fungal and insect agents. Thetraditional method of control involves application of chemicalfungicides. This adds to the cost of crop and flower production. Inaccordance with the present disclosure, a surprising synergy isidentified between a Class I defensin and a permeabilizing defensinresulting in increased efficacy in preventing and ameliorating fungaland insect disease conditions in plants. The method is also applicableto treating or preventing pathogen infestation in human and non-humananimal subjects. Reference to a “Class I” defensin includespermeabilizing and non-permeabilizing defensins. Hence, one or morepermeabilizing defensins may be employed. Reference to a “permeabilizingdefensin” includes a Class I defensin, a Class II defensin and a variantdefensin, which is a permeabilizing defensin. A “variant” defensinincludes a defensin wherein a Loop 1B region from a Class II defensin isreplaced by a Loop 1B region from a Class I defensin or the Class IILoop 1B region is otherwise subject to one or more amino acidsubstitutions, additions or deletions. The Loop 1B region is locatedbetween the first β-strand (β-strand 1) and the α-helix on the defensinN-terminal end portion (also referred to as the first flexible loop).

As indicated above, plant defensins are divided into two major classes.Class I defensins consist of an endoplasmic reticulum (ER) signalsequence followed by a mature defensin domain. Class II defensins areproduced as larger precursors with C-terminal pro-domains orpro-peptides (CTPPs) of about 33 amino acids in addition to the ERsignal sequence and mature domain.

Synergy is classified as the difference between the observed % fungalgrowth inhibition caused by the combination of two defensins (Io value)and the expected % fungal growth inhibition of the two defensins basedon the sum of the % fungal growth inhibition of each defensin on its own(Ee value calculated according to the Limpel formula used by Richer etal. (1987) Pestic Sci 19:309-315). The difference, Io-Ee, is the synergyvalue. A synergy value up to 15 means no significant synergy; 15-30 is alow level of synergy; 30-60 is a medium level of synergy; and >60 is ahigh level of synergy.

Accordingly, the present disclosure teaches a method for protecting aplant from a disease associated with infection by a pathogen, the methodcomprising providing cells with a Class I plant defensin and apermeabilizing defensin or a precursor or a functional homolog, analog,derivative or variant thereof of either or both. In an embodiment, theplant pathogen is a fungus. In another embodiment, the plant pathogen isan insect. Reference to a “plant” includes in one aspect, a geneticallymodified plant comprising cells which produce the Class I defensin and apermeabilizing defensin wherein cells, prior to genetic modification, donot produce either defensin. Reference to a “plant” includes, progeny ofthe genetically modified plant which comprise cells which produce one orother or both of the defensins as a result of the genetic modificationof the parent. The production of the two defensins resulting from thegenetic modification of the parent and this trait passed on to theprogeny confers a resistance to the fungal or insect pathogen to a levelnot observed in plants which do not produce both defensins. A Class Idefensin may be a permeabilizing defensin or a non-permeabilizingdefensin. The present disclosure further teaches a method for protectinga human or non-human animal subject from a disease associated withinfection by a pathogen, the method comprising providing cells with aClass I plant defensin and a permeabilizing defensin or a precursor or afunctional homolog, analog, derivative or variant thereof of either orboth. In an embodiment, the pathogen is a fungus. Reference to anon-human animal subject includes a farm animal (e.g. cow, sheep, pig,horse, donkey, Llama, alpaca, avian animal), domestic animal (e.g. dogs,cat), laboratory test animal (e.g. mouse, rat, guinea pig, rabbit,hamster, non-human primate) and captured wild animal.

The term “genetic modification” means that a plant or plant cell isgenetically modified by recombinant DNA technology to introduce geneticmaterial encoding both defensins. Alternatively, this technology is usedto introduce genetic material encoding at least one defensin, andconventional breeding is used to introduce another defensin gene.

In an embodiment, the Class I defensin is a permeabilizing defensin. Inanother embodiment, the Class I defensin is a non-permeabilizingdefensin. In an embodiment, the second permeabilizing defensin isselected from a Class I, Class II or variant defensin.

The present disclosure enables a method for protecting a plant frominfection by a fungal or insect pathogen and/or for reducing theincidence of severity of fungal or insect pathogen-associated disease.The instant disclosure is also useful for reducing fungal or insectinfestation on the plant and/or its surrounding root system or soil toan acceptable level. The method encompasses a multivalent approach ofusing a combination of at least one Class I defensin and onepermeabilizing defensin. An example of the latter permeabilizingdefensin is a Class I, Class II or variant defensin. Variant defensinsare taught in PCT/AU2012/000112, the contents of which are incorporatedherein by reference. Unexpectedly, the combined action of a given ClassI defensin and a given permeabilizing defensin on a given fungal orinsect pathogen is synergistic, i.e. the anti-pathogen activity of the(at least) two components is greater than the sum of the inhibitoryeffects of either defensin acting alone when they are combined in theplant environment. The level of synergy is from low to high.

Hence, the present disclosure is instructional for a method forprotecting a plant from a disease associated with infection by a fungalor insect pathogen, the method comprising providing cells of the plantswith a Class I defensin and a permeabilizing defensin or a precursor ora functional homolog, analog, derivative or variant thereof of either orboth in a synergistically effective amount to reduce infection by thepathogen.

Reference to a “method” in this context includes a plant managementsystem, a protocol and a procedure. As indicated above, in anembodiment, the pathogen is a fungal pathogen. In another embodiment,the pathogen is an insect pathogen.

Reference to “providing cells of the plant” includes providing the twodefensins from an exogenous source, or providing both from within thecell (via genetic modification) or providing one exogenously and oneintracellularly. Hence, topical application and genetic engineering maybe used and optionally further including conventional breeding togenetic plants exposed to both defensins. Further enabled herein is atopical seed coating comprising the combination of two defensins or thetopical application of one defensin to a plant or plant seed engineeredto express the other defensin.

Further enabled herein is a method for protecting a human or non-humananimal subject from a disease associated with infection by a fungal orinsect pathogen, the method comprising providing cells of the human ornon-human animal with a Class I defensin and a permeabilizing defensinor a precursor or a functional homolog, analog, derivative or variantthereof of either or both in a synergistically effective amount toreduce infection by the pathogen.

The present disclosure further contemplates the use of a Class Idefensin and a permeabilizing defensin or a precursor form of either orboth in, the manufacture of a genetically modified plant which is lesssusceptible to fungal or insect infestation or exhibits less fungal orinsect infestation-associated damage.

The present disclosure further contemplates the use of a Class Idefensin and a permeabilizing defensin or a precursor form of either orboth in the manufacture of a medicament for the treatment of a fungalinfestation in a human or non-human animal subject.

In an embodiment, a method is provided for protecting crop or ornamentalplants from fungal or insect challenge, comprising providing to theplant a Class I defensin and a permeabilizing defensin or functionalhomologs, analogs or variants or equivalents thereof. In thisembodiment, the extent of fungal or insect inhibition by both componentsis considered synergistic compared to the combined separate effects ofeach component alone. In an embodiment, there is synergistic inhibitionof Fusarium species by a combination of at least one Class I defensin,and at least one permeabilizing defensin. Examples of Class I defensinsinclude hordothionin (γ1-H), zeathionin (γ-Zea2), PsD1, DmAMP1, SBI6,VP42, VP45, VP135, RsAFP2, MsDef1, MtDef2, MtDef4, HsAFP1, VaD2, VrD2,ZmESR6 and a HXL defensin (see Table 2). Examples of a permeabilizingdefensin include NaD1, TPP3, PhD1A, PhD2, HXL001, HXL002, HXL004,HXL007, HXL008, HXP4, HXP34 and HXP35 and NoD173 (see Table 2). Thesubject method may also additionally include the use of a proteinaseinhibitor or a precursor form thereof such as a cysteine or serineproteinase inhibitor (e.g. potato StPin1A [previously referred to asPot1A (U.S. Pat. No. 7,462,695)]), HvCPI6, SICys9, At2g38870, bovinepancreatic trypsin inhibitor (BPTI) or bovine trypsin inhibitor I-P. Anyfungus or insect individually susceptible to inhibition by each of thecomponents of the system can be more effectively controlled by using thecombination than by either component used by itself. Particularly usefulcombinations include HXP4, NaD1, HXL004, HXL001 and/or HXL008 as apermeabilizing defensin and HXL012, HXL015, SB16, HXL009, HXL008 and/orHXL021 as the Class I defensin.

The instant disclosure further provides a method for protecting a plantfrom a disease associated with infection by a fungal or insect pathogen.The method comprises providing cells of a plant with a Class I defensinand a permeabilizing defensin and optionally a proteinase inhibitor or aprecursor or a functional homolog, analog, derivative or variant thereofof any one or all of these components.

The multivalent approach of the present method comprises a Class Idefensin and a permeabilizing defensin acting synergistically togetheror further comprising a proteinase inhibitor or a precursor formthereof. These components may be produced by recombinant means within aplant cell or may be provided to a plant cell topically such as in theform of a spray, aerosol, powder or as part of fertilizer or plant food.As indicated above, in yet another alternative, one component isprovided by recombinant means and another component is providedexogenously. Topical seed coatings, are enabled herein. Both defensinsmay be applied to the seed coat or one defensin is topically applied toa plant or seed which has been engineered to express another defensin.In an embodiment, one or other defensin is provided by geneticengineering means and the other defensin is introduced by conventionalbreeding.

Another aspect taught herein is a method for inhibiting fungal or insectgrowth, replication, infection and/or maintenance, the method comprisingexposing the fungus or insect to a combination of a Class I defensin anda permeabilizing defensin. A proteinase inhibitor or precursor formthereof may also be used. This applies to plants and human and non-humananimal subjects.

Again, the extent of fungal or insect inhibition in the presence of bothdefensins is synergistic as compared to the sum of inhibition providedby either component in individual contact with the fungus at the samedose used for the combined exposure.

A fungus or an insect is “susceptible to inhibition” by each of theindividual components of the system if it can be shown that eachcomponent individually exerts an inhibitory activity against the fungusor insect, or the components in combination exert a combined inhibitoryeffect that is synergistic.

Chimeric defensin molecules and/or defensin variants which retainanti-fungal activity can also be employed in the present method forplant protection based on whether the chimeric defensin is regarded as aClass I defensin or a permeabilizing defensin or both.

Further enabled herein is a multigene expression vehicle (MGEV)comprising a polynucleotide having 2 to 8 domain segments, each domainencoding a functional protein wherein at least one domain encodes aClass I defensin and at least one other domain encodes a permeabilizingdefensin, each domain being joined to the next in a linear sequence by alinker sequence encoding a linker peptide having the amino acid sequenceset forth in SEQ ID NO:86. The MGEV vector is disclosed in USSN2007-0277263, the contents of which are incorporated herein byreference.

In an embodiment, at least one other domain encodes a proteinaseinhibitor or a precursor form thereof.

The linker peptide comprises the amino acid sequence X₁X₂X₃X₄X₅ (SEQ IDNO:86) wherein:

-   X₁=E or D-   X₂=E or D-   X₃=K or R-   X₄=K or R-   X₅=N or Q.

The present disclosure further teaches the use of a Class I defensin anda permeabilizing defensin and optionally a proteinase inhibitor or afunctional homolog, analog, derivative or variant thereof of any one orall of these components in the manufacture of a genetically modifiedplant or its progeny resistant to fungal or insect pathogen infestation.

The present disclosure further teaches the use of a Class I defensin anda permeabilizing defensin and optionally a proteinase inhibitor or afunctional homolog, analog, derivative or variant thereof of any one orall of these components in a human or non-human animal subject or itsprogeny resistant to fungal or insect pathogen infestation.

Proteinase inhibitors useful in embodiments of the present methodinclude but are not limited to cysteine and serine proteinaseinhibitors.

Plants which can be protected from fungal or insect infestation by theinstant method include those which are susceptible to a fungus or insectwhich is sensitive to a proteinase inhibitor and a plant defensin whichcan be expressed as transgenes in that plant or to which a compositioncomprising the defensin and proteinase inhibitor, can be applied.

A combined transgene and topical application approach is alsocontemplated herein. A “topical application approach” includes seedcoatings. The proteinase inhibitor is generally a protein or a peptideor a chemical analog thereof. The plant can be a monocotyledonous plantor dicotyledonous plant. Particular plants include corn (maize),soybean, cotton, canola and wheat and the like, as well as plants of thefamilies Solanaceae, Brassicaceae, Malvaceae, and Fabaceae.

Infection and damage from many fungal pathogens, especially those whichare filamentous fungi, can be controlled in many plant species using thepresent system. Examples of controllable fungal and oomycete pathogensinclude, but are not limited to, Fusarium, Verticillium, Pythium,Rhizoctonia, Sclerotinia, Leptosphaeria, Phytophthora, Colletotrichum,Cercospora and Alternaria species, and rust fungi. Importantapplications include, without being limiting, the synergisticcombinations of a proteinase inhibitor and an antifungal defensin used,e.g. to protect plants from Fusarium graminearum (Fgr), Fusariumoxysporum f. sp. vasinfectum (Fov), Colletotrichum graminicola (Cgr),Leptosphaeria maculans, Alternaria brassicicola, Alternaria alternata,Aspergillus nidulans, Botrytis cinerea, Cercospora beticola, Cercosporazeae maydis, Cochliobolus heterostrophus, Exserohilum turcicum, Fusariumculmorum, Fusarium oxysporum, Fusarium oxysporum f. sp. dianthi,Fusarium oxysporum f. sp. lycopersici, Fusarium solani, Fusariumpseudograminearum, Fusarium verticilloides (Fve), Gaeumannomycesgraminis var. tritici, Plasmodiophora brassicae, Sclerotiniasclerotiorum, Stenocarpella (Diplodia) maydis; Thielaviopsis basicola,Verticillium dahliae, Ustilago zeae, Puccinia sorghi, Macrophominaphaseolina, Phialophora gregata, Diaporthe phaseolorum, Cercosporasojina, Phytophthora sojae, Rhizoctonia solani, Phakopsora pachyrhizi,Alternaria macrospora, Cercospora gossypina, Phoma exigua, Pucciniaschedonnardii, Puccinia cacabata, Phymatotrichopsis omnivora, Fusariumavenaceum, Alternaria brassicae, Alternaria raphani, Erysiphe graminis(Blumeria graminis), Septoria tritici, Septoria nodorum; Mycosphaerellazeae, Rhizoctonia cerealis, Ustilago tritici, Puccinia graminis,Puccinia triticina, Tilletia indica, Tilletia caries, and Tilletiacontroversa.

Insect pathogens include Diatraea grandiosella, Ostrinia nubialis,Rhopalosiphum spp, Helicoverpa spp, Plutella xylostella and Lygus spp.

Agronomic compositions comprising a Class I defensin and apermeabilizing defensin or anti-fungal or anti-insect homologs, analogs,variants and functional equivalents thereof or their precursor forms arealso contemplated herein. The compositions may also include a proteinaseinhibitor or a precursor form thereof. An agronomic composition includesa seed coating formulation.

A protocol for managing plant pathogen infection of plants is furthercontemplated herein comprising the manipulation of a plant environmentto provide a Class I defensin and a permeabilizing defensin in amountswhich inhibit the pathogen.

Reference to “plant pathogen” in a particular embodiment includes afungus and an insect or other related organisms. A fungus includes arust. Generally, when the method comprises genetically modifying plantsto express both defensins, the term “plant” includes its progeny. Whenthe method comprises topically applying a combination of defensins, theeffect is generally limited to a particular plant.

Whilst the instant disclosure is particularly directed toanti-phytopathogenic methods, the multivalent approach may also be usedin human and non-human subjects, including farm animals, domesticanimals, laboratory test animals and captured wild animals. Generally, atopical approach is used in these circumstances. Commonly, themultivalent approach in human and non-human subjects target inter aliayeasts such as Candida and Cryptococcus, dermatophytes such asTrichophyton including Trichophyton interdigitale and Trichophytonrubrum and other filamentous fungi including Aspergillus spp such asAspergillus niger.

Further enabled herein is a method for protecting a plant from a diseaseassociated with infection by a pathogen, the method comprising providingcells of the place with a Class I defensin having a mature domaincomprising an amino acid sequence selected from SEQ ID NOs:81, 83, 85,3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57,60, 63, 66 and 69, a permeabilizing defensin having a mature domainselected from the listing consisting of NaD1, TPP3; PhD1A, PhD2, NoD173,SEQ ID NOs:3, 6, 12, 21, 24, 70, 71 and 72 or a precursor or afunctional homolog, analog, derivative or variant thereof of either orboth.

Further enabled herein is a method for protecting a plant from a diseaseassociated with infection by a pathogen, the method comprising providingcells of the place with a Class I defensin having a mature domaincomprising an amino acid sequence selected from SEQ ID NOs:81, 83, 85,3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57,60, 63, 66 and 69, a permeabilizing defensin having a mature domainselected from the listing consisting of SEQ ID NOs:3, 6, 12, 21, 24, 70,71 and 72 or a precursor or a functional homolog, analog, derivative orvariant thereof of either or both.

Further enabled herein is a method for protecting a human or non-humananimal subject from a disease associated with infection by a pathogen,the method comprising providing cells of the place with a Class Idefensin having a mature domain comprising an amino acid sequenceselected from SEQ ID NOs:81, 83, 85, 3, 6, 9, 12, 15, 18, 21, 24, 27,30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66 and 69, apermeabilizing defensin having a mature domain selected from the listingconsisting of NaD1, TPP3, PhD1A, PhD2, NoD173, SEQ ID NOs:3, 6, 12, 21,24, 70, 71 and 72 or a precursor or a functional homolog, analog,derivative or variant thereof of either or both.

TABLE 1 Summary of Sequence Identifiers Peptide Source Sequence typeSequence ID HXL001 Zea mays Full length nucleic acid SEQ ID NO: 1 (NA)Full length protein SEQ ID NO: 2 Mature domain SEQ ID NO: 3 HXL002Triticum aestivum Full length NA SEQ ID NO: 4 Full length protein SEQ IDNO: 5 Mature domain SEQ ID NO: 6 HXL003 Triticum aestivum Full length NASEQ ID NO: 7 Full length protein SEQ ID NO: 8 Mature domain SEQ ID NO: 9HXL004 Nicotiana benthamiana Full length NA SEQ ID NO: 10 Full lengthprotein SEQ ID NO: 11 Mature domain SEQ ID NO: 12 HXL005 Taraxacumkok-saghyz Full length NA SEQ ID NO: 13 Full length protein SEQ ID NO:14 Mature domain SEQ ID NO: 15 HXL006 Triticum aestivum Full length NASEQ ID NO: 16 Full length protein SEQ ID NO: 17 Mature domain SEQ ID NO:18 HXL007 Cyamopsis Full length NA SEQ ID NO: 19 tetragonoloba Fulllength protein SEQ ID NO: 20 Mature domain SEQ ID NO: 21 HXL008Picramnia pentandra Full length NA SEQ ID NO: 22 Full length protein SEQID NO: 23 Mature domain SEQ ID NO: 24 HXL009 Zea mays Full length NA SEQID NO: 25 Full length protein SEQ ID NO: 26 Mature domain SEQ ID NO: 27HXL010 Triticum aestivum Full length NA SEQ ID NO: 28 Full lengthprotein SEQ ID NO: 29 Mature domain SEQ ID NO: 30 HXL011 Eucalyptusgrandis Full length NA SEQ ID NO: 31 Full length protein SEQ ID NO: 32Mature domain SEQ ID NO: 33 HXL012 Amaranthus retroflexus Full length NASEQ ID NO: 34 Full length protein SEQ ID NO: 35 Mature domain SEQ ID NO:36 HXL013 Glycine max Full length NA SEQ ID NO: 37 Full length proteinSEQ ID NO: 38 Mature domain SEQ ID NO: 39 HXL014 Tulipa gesneriana Fulllength NA SEQ ID NO: 40 Full length protein SEQ ID NO: 41 Mature domainSEQ ID NO: 42 HXL015 Oryza sativa Full length NA SEQ ID NO: 43 Fulllength protein SEQ ID NO: 44 Mature domain SEQ ID NO: 45 HXL016 Triticumaestivum Full length NA SEQ ID NO: 46 Full length protein SEQ ID NO: 47Mature domain SEQ ID NO: 48 HXL017 Zea mays Full length NA SEQ ID NO: 49Full length protein SEQ ID NO: 50 Mature domain SEQ ID NO: 51 HXL018Parthenium argentatum Full length NA SEQ ID NO: 52 Full length proteinSEQ ID NO: 53 Mature domain SEQ ID NO: 54 HXL019 Nicotiana benthamianaFull length NA SEQ ID NO: 55 Full length protein SEQ ID NO: 56 Maturedomain SEQ ID NO: 57 HXL020 Triticum aestivum Full length NA SEQ ID NO:58 Full length protein SEQ ID NO: 59 Mature domain SEQ ID NO: 60 HXL021Arachis hypogaea Full length NA SEQ ID NO: 61 Full length protein SEQ IDNO: 62 Mature domain SEQ ID NO: 63 HXL022 Cyamopsis Full length NA SEQID NO: 64 tetragonoloba Full length protein SEQ ID NO: 65 Mature domainSEQ ID NO: 66 HXL023 Triticum aestivum Full length NA SEQ ID NO: 67 Fulllength protein SEQ ID NO: 68 Mature domain SEQ ID NO: 69 HXP4 ArtificialProtein SEQ ID NO: 70 HXP34 Artificial Protein SEQ ID NO: 71 HXP35Artificial Protein SEQ ID NO: 72 HXP37 Artificial Protein SEQ ID NO: 73HXP58 Artificial Protein SEQ ID NO: 74 HXP72 Artificial Protein SEQ IDNO: 75 HXP91 Artificial Protein SEQ ID NO: 76 HXP92 Artificial ProteinSEQ ID NO: 77 HXP95 Artificial Protein SEQ ID NO: 78 HXP107 ArtificialProtein SEQ ID NO: 79 VP42 Triticum aestivum Full length protein SEQ IDNO: 80 VP42 Triticum aestivum Mature domain SEQ ID NO: 81 VP45 Zea maysFull length protein SEQ ID NO: 82 VP45 Zea mays Mature domain SEQ ID NO:83 VP135 Picramnia pentandra Full length protein SEQ ID NO: 84 VP135Picramnia pentandra Mature domain SEQ ID NO: 85 Linker Artificial — SEQID NO: 86 (for a MGEV) HXL032 Triticum aestivum Full length NA SEQ IDNO: 87 HXL032 Triticum aestivum Full length protein SEQ ID NO: 88 HXL032Triticum aestivum Mature domain SEQ ID NO: 89 HXL033 Partheniumargentatum Full length NA SEQ ID NO: 90 HXL033 Parthenium argentatumFull length protein SEQ ID NO: 91 HXL033 Parthenium argentatum Maturedomain SEQ ID NO: 92 HXL034 Nicotiana benthamiana Full length NA SEQ IDNO: 93 HXL034 Nicotiana benthamiana Full length protein SEQ ID NO: 94HXL034 Nicotiana benthamiana Mature domain SEQ ID NO: 95 NoD173Nicotiana occidentalis Full length NA SEQ ID NO: 96 NoD173 Nicotianaoccidentalis Full length protein SEQ ID NO: 97 NoD173 Nicotianaoccidentalis Mature domain SEQ ID NO: 98

TABLE 2 Examples of plant defensins Type Accession (Class I, Class HPeptide Source number or variant) Permeabilizing Reference NaD1Nicotiana alata Q8GTM0 Class II Yes Lay et al, 2003 PhD1A Petuniahybrida Q8H6Q1 Class II Yes Lay et al, 2003 PhD2 Petunia hybrida Q8H6Q0Class II Yes Lay et al, 2003 TPP3 Solanum lycopersicum AAA80496 Class IIYes Milligan & Gasser, 1995 MtDef4 Medicago truncatula Class I Sagaramet al, 2011 VP42 Triticum aestivum Class I No SEQ ID NO: 81 VP45 Zeamays Class I No SEQ ID NO: 83 VP135 Picramnia pentandra Class I No SEQID NO: 85 SBI6 Glycine max Class I SEQ ID NO: 39 γ1-H Hordeum vulgareP20230 Class I No Mendez et al, 1990 γ-Zea2 Zea mays P81009 Class ICastro et al, 1996 RsAFP2 Raphanus sativus P30230 Class I No Terras etal, 1992 DmAMP1 Dahlia merckii AAB34972 Class I No Osborn et al, 1995MsDefl Medicago sativa AAV85437 Class I Hanks et al, 2005 MtDef2Medicago truncatula AY313169 Class I Spelbrink et al, 2004 PsD1 Pisumsativum P81929 Class I Almeida et al, 2000 HsAFP1 Heuchera sanguineaAAB34974 Class I Osborn et al, 1995 VaD1 Vigna angularis n/a Class IChen et al, 2005 VrD2 Vigna radiata 2GL1_A Class I Lin et al, 2007ZmESR6 Zea mays CAH61275 Class I Balandin et al, 2005 HXL001 Zea mays —Class I Yes SEQ ID NO: 3 HXL002 Triticum aestivum — Class I Yes SEQ IDNO: 6 HXL003 Triticum aestivum — Class I SEQ ID NO: 9 HXL004 Nicotianabenthamiana — Class I Yes SEQ ID NO: 12 HXL005 Taraxacum kok-saghyz —Class I No SEQ ID NO: 15 HXL006 Triticum aestivum — Class I SEQ ID NO:18 HXL007 Cyamopsis tetragonoloba — Class I Yes SEQ ID NO: 21 HXL008Picramnia pentandra — Class I Yes SEQ ID NO: 24 HXL009 Zea mays — ClassI No SEQ ID NO: 27 HXL010 Triticum aestivum — Class 1 SEQ ID NO: 30HXL011 Eucalyptus grandis — Class I SEQ ID NO: 33 HXL012 Amaranthusretrollexus — Class I SEQ ID NO: 36 HXL013 Glycine max — Class I Yes SEQID NO: 39 HXL014 Tulipa gesneriana — Class I SEQ ID NO: 42 HXL015 Oryzasativa — Class I No SEQ ID NO: 45 HXL016 Triticum aestivum — Class I SEQID NO: 48 HXL017 Zea mays — Class I SEQ ID NO: 51 HXL018 Partheniumargentatum — Class I SEQ ID NO: 54 HXL019 Nicotiana benthamiana — ClassI SEQ ID NO: 57 HXL020 Triticum aestivum — Class I SEQ ID NO: 60 HXL021Arachis hypogaea — Class I No SEQ ID NO: 63 HXL022 Cyamopsistetragonoloba — Class I SEQ ID NO: 66 HXL023 Triticum aestivum — Class ISEQ ID NO: 69 HXP4 Artificial Variant Yes SEQ ID NO: 70 HXP34 ArtificialVariant Yes SEQ ID NO: 71 HXP35 Artificial Variant Yes SEQ ID NO: 72HXP37 Artificial Variant SEQ ID NO: 73 HXP58 Artificial Variant SEQ IDNO: 74 HXP72 Artificial Variant SEQ ID NO: 75 HXP91 Artificial VariantSEQ ID NO: 76 HXP92 Artificial Variant SEQ ID NO: 77 HXP95 ArtificialVariant SEQ ID NO: 78 HXP107 Artificial Variant SEQ ID NO: 79 HXL032Triticum aestivum Class I SEQ ID NO: 89 HXL033 Parathenium argentatumClass I SEQ ID NO: 92 HXL034 Nicotiana benthamiana Class I SEQ ID NO: 95NoD173 Nicotiana occidentalis sppoblique Class II Yes SEQ ID NO: 98

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graphical representation showing the results of apermeabilization assay on Fov hyphae demonstrating the differencebetween permeabilizing (NaD1, HXP4, HXL002, HXL007 and HXL008) andnon-permeabilizing (DmAMP1) defensins.

FIG. 2 is a graphical representation showing the results of apermeabilization assay on Fgr hyphae demonstrating the differencebetween permeabilizing (NaD1, HXP4, HXL002, HXL004, HXL008 and HXL013)and non-permeabilizing (Hordothionin, RsAFP2, HXL009 and HXL021)defensins.

DETAILED DESCRIPTION

A phytopathogenic fungus includes but is not limited to Fusariumgraminearum (Fgr), Fusarium oxysporum f. sp. vasinfectum (Fov),Colletotrichum graminicola (Cgr), Leptosphaeria maculans, Alternariabrassicicola, Alternaria alternata, Aspergillus nidulans, Botrytiscinerea, Cercospora beticola, Cercospora zeae maydis, Cochliobolusheterostrophus, Exserohilum turcicum, Fusarium culmorum, Fusariumoxysporum, Fusarium oxysporum f. sp. dianthi, Fusarium oxysporum f. sp.lycopersici, Fusarium solani, Fusarium pseudograminearum, Fusariumverticilloides (Fve), Gaeumannomyces graminis var. tritici,Plasmodiophora brassicae, Sclerotinia sclerotiorum, Stenocarpella(Diplodia) maydis, Thielaviopsis basicola, Verticillium dahliae,Ustilago zeae, Puccinia sorghi, Macrophomina phaseolina, Phialophoragregata, Diaporthe phaseolorum, Cercospora sojina, Phytophthora sojae,Rhizoctonia solani, Phakopsora pachyrhizi, Alternaria macrospora,Cercospora gossypina, Phoma exigua, Puccinia schedonnardii, Pucciniacacabata, Phymatotrichopsis omnivora, Fusarium avenaceum, Alternariabrassicae, Alternaria raphani, Erysiphe graminis (Blumeria graminis),Septoria tritici, Septoria nodorum, Mycosphaerella zeae, Rhizoctoniacerealis, Ustilago tritici, Puccinia graminis, Puccinia triticina,Tilletia indica, Tilletia caries and Tilletia.

A fungal pathogen of human and non-human subjects includes yeasts suchas Candida and Cryptococcus, dermatophytes such as Trichophyton such asTrichophyton interdigitale and Trichophyton rubrum and other filamentousfungi including Aspergillus spp such as Aspergillus niger.

A phytopathogenic insect includes Diatraea grandiosella, Ostrinianubialis, Rhopalosiphum spp, Helicoverpa spp, Plutella xylostella andLygus spp.

Reference to “variant” includes a derivative of a particular sequence aswell as a natural variant such as a polymorphic variant. It alsoincludes synthetic variants such as defensins comprising a heterologousdomain or loop such as from another defensin, such as described inPCT/AU2012/000112, the contents of which are incorporated herein byreference.

The inhibitory effect of a given pair of defensins is proposed herein tobe synergistic. Greco et al. (1995) Pharmacol Rev 47:331-385 has defineddifferent categories of synergy, according to whether one, both orneither of the two components has measurable activity when assayed inthe absence of the other component. The definition adopted hereinincludes all such situations provided that the combined effect of thetwo components acting together is greater than the sum of the individualcomponents acting alone. It will be understood that a synergisticcombination of two or more components may yield greater than additiveactivity only under certain conditions; e.g. when one or more of thecomponents is present at a lower concentration than is maximal forindividual efficacy. A combination of components is deemed synergistic,as the term is intended herein, if there exists a set of conditions,including but not limited to concentrations, where the combined effectof the components acting together is greater than the sum of theindividual components acting alone. Richer (1987) supra describes amathematical approach to establish proof of synergy. This approach usesLimpel's formula which is defined in Richer (1987) supra and was used byHarman et al. U.S. Pat. No. 6,512,166 to prove synergy between fungalcell wall degrading enzymes and fungal cell membrane affecting compoundson the growth of plant pathogenic fungi. A similar approach can be usedfor insects.

Synergy is classified as the difference between the observed % fungalgrowth inhibition caused by the combination of two defensins (Io value)and the expected % fungal growth inhibition of the two defensins basedon the sum of the % fungal growth inhibition of each defensin on its own(Ee value calculated according to the Limpel formula used by Richer etal. (1987) supra). The difference, Io-Ee, is the synergy value. Asynergy value up to 15 means no significant synergy; 15-30 is a lowlevel of synergy; 30-60 is a medium level of synergy; and >60 is a highlevel of synergy.

“Fungal inhibition” includes both fungicidal and fungi static activity,as measured by reduction of fungal growth (or loss of viability)compared to a control. Fungal growth can be measured by many differentmethods known in the art. A commonly used method of measuring growth ofa filamentous fungus entails germinating spores in a suitable growthmedium, incubating for a time sufficient to achieve measurable growth,and measuring increased optical density in the culture after a specifiedincubation time. The optical density is increased with increased growth.Typically, fungal growth is necessary for pathogenesis. Therefore,inhibition of fungal growth provides a suitable indicator for protectionfrom fungal disease, i.e. the greater the inhibition, the more effectivethe protection. Similarly, “insect inhibition” include both insecticidaland insectistatic activity. Anti-insect activity can be usefullymeasured in feeding trials.

“Preventing infection” in the present context, means that the plants orhuman or non-human animal subjects treated by the method of the presentinvention, avoid pathogen infection or disease symptoms or all of theabove, or exhibit reduced or minimized or less frequent pathogeninfection or disease symptoms or all of the above, that are the naturaloutcome of the subject-pathogen interactions when compared to plants notexpressing the two defensin transgenes or treated with the twodefensins. That is to say, pathogens are prevented or reduced fromcausing disease and/or the associated disease symptoms. Infection and/orsymptoms are reduced at least about 10%, 20%, 30%, 40%, 50%, 60%, 70% or80% or greater as compared to a plant not so treated with the methodtaught herein. In an aspect, the method herein disclosed results inreduced sporulation of the pathogenic fungus to a greater extent in thepresence of both defensins.

Hence, the combined action of the defensins is to inhibit fungal growth,replication, infection and/or maintenance, amongst other inhibitoryactivities and/or to inhibit insect infestation.

Plant protection (disease resistance or reduction) can be evaluated bymethods known in the art. See, Uknes (1993) Molecular Plant MicrobeInteractions 6:680-685; Gorlach et al. (1996) Plant Cell 8:629-643;Alexander et al. (1993) Proc Natl Acad Sci USA 90:7327-7331. The skilledartisan will recognize that methods for determining plant infection anddisease by a plant pathogen depends on the pathogen and plant beingtested.

Reference to a “Class I” defensin includes permeabilizing andnon-permeabilizing defensins. Reference to a “permeabilizing defensin”includes a Class I defensin, a Class II defensin and a variant defensin,which is a permeabilizing defensin. A “variant” defensin includes adefensin wherein a Loop 1B region from a Class II defensin is replacedby a Loop 1B region on a Class I defensin or the Class II Loop 1B regionis otherwise subject to one or more amino acid substitutions, additionsor deletions. The Loop 1B region is located between the first n-strand(β-strand 1) and the α-helix on the defensin N-terminal end portion(also referred to as the first flexible loop). As indicated above, plantdefensins are divided into two major classes. Class I defensins consistof an endoplasmic reticulum (ER) sequence followed by a mature defensindomain. Class II defensins are produced as larger precursors withC-terminal pro-domains or pro-peptides (CTPPs) of about 33 amino acidsin addition to the ER signal sequence and mature domain.

A permeabilizing defensin is one which permits entry of a DNA-bindingdye such as SYTOX (Registered Trade Mark) into hyphal cells. Forexample, hyphae are grown and incubated with the DNA binding dye for 10minutes prior to addition of a peptide to be tested for its ability tobe permeabilizing. DNA-binding dye-uptake is then measured. In the caseof SYTOX, measurement is by fluorescence with excitation and emissionwavelengths of 488 nm and 538 nm, respectively. Conveniently, thepermeabilizing assay is conducted using Fusarium oxysporum f. sp.vasinfectum (Fov). In this assay, the permeabilizing defensin NaD1 isset as 1.0 and any defensin peptide giving a permeability index greaterthan 0.12 is regarded as a permeabilizing defensin. See FIG. 1 and Table12a. More information can be found in PCT/AU2009/000106.

Another assay involves Fusarium graminearum (Fgr), again using NaD1 asthe positive control, set at a permeabilization index of 1.0. See FIG. 2and Table 12b.

Reference to a Class I defensin includes hordothionin (γ1-H), zeathionin(γ-Zea2), PsD1, DmAMP1, SBI6, VP42, VP45, VP135, RsAFP2, MsDef1, MtDef2,MtDef4, HsAFP1, VaD2, VrD2, ZmESR6 or a HXL defensin (see Table 2).Reference to a permeabilizing defensin includes Class II defensins suchas NaD1, TPP3, PhD1A or PhD2, NoD173, Class I defensins such as HXL001,HXL002, HXL004, HXL007 or HXL008 or variant defensins such as HXP4,HXP34 or HXP35 (see Table 2). Particularly useful combinations includeHXP4, NaD1, HXL004, HXL001 and/or HXL008 as a permeabilizing defensinand HXL012, HXL015, SB16, HXL009, HXL008 and/or HXL021 as the Class Idefensin.

Further enabled herein is a method for protecting a plant or human ornon-human animal subject from a disease associated with infection by apathogen, the method comprising providing cells of the place with aClass I defensin having a mature domain comprising an amino acidsequence selected from SEQ ID NOs:81, 83, 85, 3, 6, 9, 12, 15, 18, 21,24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66 and 69, apermeabilizing defensin having a mature domain selected from the listingconsisting of NaD1, TPP3, PhD1A, PhD2, NoD173, SEQ ID NOs:3, 6, 12, 21,24, 70, 71 and 72 or a precursor or a functional homolog, analog,derivative or variant thereof of either or both.

Further enabled herein is a method for protecting a plant or human ornon-human animal subject from a disease associated with infection by apathogen, the method comprising providing cells of the place with aClass I defensin having a mature domain comprising an amino acidsequence selected from SEQ ID NOs:81, 83, 85, 3, 6, 9, 12, 15, 18, 21,24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66 and 69, apermeabilizing defensin having a mature domain selected from the listingconsisting of SEQ ID NOs:3, 6, 12, 21, 24, 70, 71 and 72 or a precursoror a functional homolog, analog, derivative or variant thereof of eitheror both.

The term “proteinase inhibitor” is used herein to include proteins orpeptides used to inhibit the activity of fungal or insect proteinasesand to protect plants or human or non-human animal subjects from fungalor insect disease. Chemical analogs or functional equivalents of theproteinase inhibitors are also encompassed herein.

The proteinase inhibitor may also be provided in a precursor form whichis processed into an active form prior to being effective.

Cysteine proteinase inhibitors, or cystatins, are tight and reversiblybinding inhibitors of cysteine proteases. They comprise a super familysubdivided into three families: the stefins, the cystatins and thekininogens (Turk and Bode (1991) FEBS Lett. 285:213-219).

Serine proteinase inhibitors, or serine endopeptidases, cleave peptidebonds in which serine serves as the nucleophilic amino acid. There aregenerally two categories: chymotrypsin-like, which includes trypsin-likechymotroypsin-like and elastase-like; and subtilisin-like (Madala et al.(2010) Chem Rev 110(6):1-31).

A “synergistic effect” occurs where two or more components within themethod produce a combined effect that is greater than the sum of theindividual effects of each component acting alone. The effect may be oneor more of efficacy, stability, rate, and/or level of toxicity. Asdescribed herein, synergistic pathogen growth inhibition measured in thecombined presence of a Class I defensin and a permeabilizing defensin isgreater than the summed inhibition measured in the presence of aparticular concentration range of each defensin component, individually,under otherwise identical conditions. It will be understood that it isnot necessary that a greater than additive effect be observed with everycombination of concentrations of the two components in order to bedeemed synergistic. The synergistic effect of two components can beobserved under certain concentration combinations, but not in others.For example, if the inability to enter the fungal cell limits toxicity,the presence of a permeabilizing defensin can result in synergy withrespect to a second defensin, especially if the concentration ofdefensin is sub-maximal with respect to inhibition. In an embodiment,the concentration of one or both of the defensin(s) is sub-maximal. Bythe same token, synergy can be masked if one or both components ispresent at such a high level (maximum level) as to result in maximumobservable inhibition. The general system for a defensin-defensincombination is, therefore, termed “synergistic” because the potentialfor synergy is present even if synergy is not observed under allconditions. The synergy between two plant defensins provides greaterfungal inhibition than can be obtained by either component acting alone,for at least some dosages. The present disclosure teaches increasedprotection of plants from fungal disease and insect infestation withreduced dependence on chemical fungicides or insecticides. This meansdecreased input cost to growers, a broader spectrum of activity againstplant pathogens and reduced potential for environmental damage. Inaddition, the selection pressure for development ofpathogenicide-resistant pathogen strains is greatly reduced, whichallows for an extended commercial life as well as reduced proliferationof resistant fungus strains and reduced likelihood of emergence ofmultiple-resistant strains.

Hence, the method of the present disclosure is useful for reducingeconomic loss due to fungal or insect infection or infestation. It alsofacilitates amelioration of disease or symptoms of disease followingpathogen exposure to human and non-human animal subjects.

In an aspect taught herein, a method is provided for the protection of aplant from a disease associated with a pathogen such as a fungal orinsect agent, and that prevention or treatment results in decreased needfor pathogenicide treatment of plants or plant parts, thus loweringcosts of material, labor, and environmental pollution, or prolongingshelf-life of products (e.g. fruit, seed, and the like) of such plants.

In an embodiment, the pathogen is a fungus. Reference to a non-humananimal subject includes a farm animal (e.g. cow, sheep, pig, horse,donkey, Llama, alpaca, avian animal), domestic animal (e.g. dogs, cat),laboratory test animal (e.g. mouse, rat, guinea pig, rabbit, hamster,non-human primate) and captured wild animal.

The term “plant” includes whole plants and parts thereof, including, butnot limited to, shoots, vegetative organs/structures (e.g. leaves, stemsand tubers), roots, flowers and floral organs/structures (e.g. bracts,sepals, petals, stamens, carpels, anthers and ovules), seed (includingembryo, endosperm, and seed coat) and fruit (the mature ovary), planttissue (e.g. vascular tissue, ground tissue, and the like) and cells(e.g. guard cells, egg cells, and the like), and progeny of same. Theplants that can be protected using the method herein described includehigher and lower plants, including angiosperms (monocotyledonous anddicotyledonous plants), gymnosperms, ferns, horsetails, psilophytes,lycophytes, bryophyte, and multicellular algae. Plants for use in thesubject method include any vascular plant, for example monocotyledons ordicotyledons or gymnosperms, including, but not limited to, corn (andmaize), soybean, cotton, cottonseed, canola, wheat, alfalfa, apple,Arabidopsis, banana, barley, castor bean, chrysanthemum, clover, cocoa,coffee, crambe, cranberry, cucumber, dendrobium, dioscorea, eucalyptus,fescue, flax, gladiolus, liliacea, linseed, millet, muskmelon, mustard,oat, oil palm, oilseed rape (rape, rapa), papaya, peanut, pineapple,ornamental plants, Phaseolus, potato, rapeseed, rice, rye, ryegrass,safflower, sesame, sorghum, sugarbeet, sugarcane, sunflower, strawberry,tobacco, tomato, turfgrass and vegetable crops such as lettuce, celery,broccoli, cauliflower, cucurbits, onions (including garlic, shallots,leeks, and chives); fruit and nut trees, such as apple, pear, peach,orange, grapefruit, lemon, lime, almond, pecan, walnut, hazelnut; vines,such as grapes, kiwifruit, hops; fruit shrubs and brambles, such asraspberry, blackberry, gooseberry; and forest trees, such as ash, pine,fir, maple, oak, chestnut and poplar.

Particular plants contemplated herein include corn, soybean, cotton,canola and wheat.

Reference to “insect pathogen” includes insects of the following phyla:Diatraea grandiosella, Ostrinia nubialis, Rhopalosiphum spp, Helicoverpaspp, Plutella xylostella and Lygus spp.

A “transgenic plant” refers to a plant, or seed thereof or its progeny,that contains genetic material not found (i.e. “exogenous”) in awild-type plant of the same species, variety or cultivar. The geneticmaterial may include a transgene, an insertional mutagenesis event (suchas by transposon or T-DNA insertional mutagenesis), an activationtagging sequence, a mutated sequence, a homologous recombination eventor a sequence modified by chimeraplasty. Typically, the foreign geneticmaterial has been introduced into the plant by human manipulation, butany method can be used as one of skill in the art recognizes. The term“genetically modified plant” may also be used which has the same meaningas a “transgenic plant” in this context. In an embodiment, the plant orpart thereof such as a seed is genetically modified to express onedefensin and the second defensin is exogenously supplied such as a seedcoating or a topical formulation.

A transgenic plant may contain an expression vector or cassette. Theexpression cassette typically comprises a polypeptide-encoding sequenceoperably linked (i.e. under regulatory control of) to appropriateinducible or constitutive regulatory sequences that allow for theexpression of the polypeptide. The expression cassette can be introducedinto a plant by transformation or by breeding after transformation of aparent plant. An example of a suitable expression cassette is disclosedin U.S. patent application Ser. No. 11/753,072 [equivalent ofPCT/AU2007/000712] the contents of which are incorporated herein byreference.

The plant or plant part for use in the present method includes plants ofany stage of plant development. Conveniently, the application occursduring the stages of germination, seedling growth, vegetative growth,and reproductive growth. Particular, applications of the present methodoccur during vegetative and reproductive growth stages. The stages ofvegetative and reproductive growth are also referred to herein as“adult” or “mature” plants. A combination of plant genetic engineeringand topical application of a defensin is also taught herein.Furthermore, one or other of the defensins may be introduced by geneticengineering means and the other is introduced by conventional breedingpractices.

Whilst the present disclosure provides a method for protecting plantsfrom fungal or insect infection using the synergistic action between aClass I defensin and a permeabilizing defensin, it is understood thatadditional materials can be added to the combination to achieve evenmore benefit with respect to the health of the plant, for example, byincorporating a proteinase inhibitor, or a fungicidal or insecticidalprotein, or by utilizing more than one of either or both of the twotypes of defensins. For example, the spectrum of activity against plantpathogens can potentially be expanded by using additional agents.

The defensin components are conveniently supplied by the plant that isto be protected after genetic modification, although the present methodextends to surface sprays or seed coatings as well as incorporation infertilizers and plant food. In an embodiment, the plant is geneticallymodified to express the desired two defensins using methods well-knownin the art.

Plant protection (disease resistance or reduction) can be evaluated bymethods known in the art. See, Uknes (1993) Molecular Plant MicrobeInteractions 6-680-685; Gorlach et al. (1996) supra; Alexander et al.(1993) supra. The skilled artisan will recognize that methods fordetermining plant infection and disease by a plant pathogen depends onthe pathogen and plant being tested.

Further enabled herein is a method for protecting a human or non-humananimal subject from a disease associated with infection by a fungal orinsect pathogen, the method comprising providing cells of the human ornon-human animal with a Class I defensin and a permeabilizing defensinor a precursor or a functional homolog, analog, derivative or variantthereof of either or both in a synergistically effective amount toreduce infection by the pathogen.

The present disclosure further contemplates the use of a Class Idefensin and a permeabilizing defensin or a precursor form of either orboth in the manufacture of a medicament for the treatment of a fungalinfestation in a human or non-human animal subject.

As indicated above, the Class I defensin may be a permeabilizing ornon-permeabilizing defensin. Hence, one or two permeabilizing defensinsmay be used.

In an embodiment, the nucleic acid is operably linked to a promoter andintroduced into the genome of a plant cell. Upon appropriate conditions,the promoter enables expression of the nucleic acid molecule to producean mRNA which is then translated into the defensin protein. The plantcell is used to regenerate a plant which is referred to as a“genetically modified plant”. The genetic modification is theintroduction of an expressible nucleic acid molecule to enableproduction of a defensin which in turn confers on cells of the plant,resistance to fungal pathogen infestation.

The nucleic acid sequences can be expressed in a plant cell. It isexpected that those of skill in the art are knowledgeable in thenumerous expression systems available for expression of a nucleic acidencoding a defensin protein. No attempt will be made to describe indetail the various methods known for the expression of proteins in plantcells.

As used herein, “heterologous” in reference to a nucleic acid is anucleic acid that originates from a plant species or strain different tothe intended recipient plant of the nucleic acid. For example, apromoter operably linked to a heterologous nucleotide sequence can befrom a plant species different from that from which the nucleotidesequence was derived.

By a “genetically modified plant” is meant a plant comprising cellswhich comprise a heterologous nucleic acid sequence. It may be deriveddirectly from a regenerated plant, its progeny or by a combination ofgenetic engineering and conventional breeding. A “heterologous” nucleicacid in this context means a nucleic acid encoding, one or other or bothdefensins and optionally a proteinase inhibitor or precursor formthereof.

The defensin sequences are generally provided in expression cassettes orDNA constructs for expression in the plant of interest. The cassettewill include 5′ and 3′ regulatory sequences operably linked to adefensin sequence of the invention. By “operably linked” a functionallinkage between a promoter and a second sequence, wherein the promotersequence initiates and mediates transcription of the DNA sequencecorresponding to the second sequence is intended. Generally, operablylinked means that the nucleic acid sequences being linked are contiguousand, where necessary to join two protein coding regions, contiguous andin the same reading frame. The cassette may additionally contain atleast one additional gene to be cotransformed into the organism.Alternatively, the additional gene(s) can be provided on multipleexpression cassettes.

Such an expression cassette is provided with a plurality of restrictionsites for insertion of the defensin sequence to be under thetranscriptional regulation of the regulatory regions. The expressioncassette may additionally contain selectable marker genes.

The expression cassette includes in the 5′-3′ direction oftranscription, a transcriptional and translational initiation region, adefensin DNA sequence of the invention, and a transcriptional andtranslational termination region functional in plants. Thetranscriptional initiation region, the promoter, may be native oranalogous or foreign or heterologous to the plant host. Additionally,the promoter may be the natural sequence or alternatively a syntheticsequence. By “foreign” is intended that the transcriptional initiationregion is not found in the native plant into which the transcriptionalinitiation region is introduced. As used herein, a chimeric genecomprises a coding sequence operably linked to a transcriptioninitiation region that is heterologous to the coding sequence.

Whilst it may be useful to express the sequences using heterologouspromoters, native promoter sequences may also be use.

The termination region may be native with the transcriptional initiationregion, may be native with the operably linked DNA sequence of interest,or may be derived from another source. Convenient termination regionsare available from the Ti-plasmid of A. tumefaciens, such as theoctopine synthase and nopaline synthase termination regions. See alsoGuerineau et al. (1991) Mol. Gen. Genet. 262:141-144; Proudfoot (1991)Cell 64:671-674; Sanfacon et al. (1991) Genes Dev. 5:141-149; Mogen etal. (1990) Plant Cell 2:1261-1272; Munroe et al. (1990) Gene 91:151-158;Ballas et al. (1989) Nucleic Acids Res. 17:7891-7903; and Joshi et al.(1987) Nucleic Acid Res. 15:9627-9639.

Where appropriate, the gene(s) may be optimized for increased expressionin the transformed plant cell. That is, the genes can be synthesizedusing plant-preferred codons for improved expression. See, for example,Campbell and Gowri (1990) Plant Physiol. 92:1-11 for a discussion ofhost-preferred codon usage. Methods are available in the art forsynthesizing plant-preferred genes. See, for example, U.S. Pat. Nos.5,380,831, 5,436,391, and Murray et al. (1989) Nucleic Acids Res.17:477-498.

Additional sequence modifications are known to enhance gene expressionin a cellular host. These include elimination of sequences encodingspurious polyadenylation signals, exon-intron splice site signals,transposon-like repeats, and other such well-characterized sequencesthat may be deleterious to gene expression. The G-C content of thesequence may be adjusted to levels average for a given cellular host, ascalculated by reference to known genes expressed in the host cell. Whenpossible, the sequence is modified to avoid predicted hairpin secondarymRNA structures.

The expression cassettes may additionally contain 5′ leader sequences inthe expression cassette construct. Such leader sequences can act toenhance translation. Translation leaders are known in the art andinclude: picornavirus leaders, for example, EMCV leader(Encephalomyocarditis 5′ noncoding region) (Elroy-Stein et al. (1989)PNAS USA 86:6126-6130); potyvirus leaders, for example, TEV leader(Tobacco Etch Virus) [Allison et al. (1986); MDMV leader (Maize DwarfMosaic Virus); Virology 154:9-20], and human immunoglobulin heavy-chainbinding protein (BiP), (Macejak et al. (1991) Nature 353:90-94);untranslated leader from the coat protein mRNA of alfalfa mosaic virus(AMV RNA 4) [Jobling et al. (1987) Nature 325:622-625]; tobacco mosaicvirus leader (TMV) (Gallie et al. (1989) In Molecular Biology of RNA,ed. Cech (Liss, New York), pp. 237-256); and maize chlorotic mottlevirus leader (MCMV) [Lommel et al. (1991) Virology 81:382-385]. Seealso, Della-Cioppa et al. (1987) Plant Physiol. 84:965-968. Othermethods known to enhance translation can also be utilized, for example,introns, and the like.

In preparing the expression cassette, the various DNA fragments may bemanipulated, so as to provide for the DNA sequences in the properorientation and, as appropriate, in the proper reading frame. Towardthis end, adapters or linkers may be employed to join the DNA fragmentsor other manipulations may be involved to provide for convenientrestriction sites, removal of superfluous DNA, removal of restrictionsites, or the like. For this purpose, in vitro mutagenesis, primerrepair, restriction, annealing, resubstitutions, e.g., transitions andtransversions, may be involved.

Generally, the expression cassette will comprise a selectable markergene for the selection of transformed cells. Selectable marker genes areutilized for the selection of transformed cells or tissues. Marker genesinclude genes encoding antibiotic resistance, such as those encodingneomycin phosphotransferase II (NEO) and hygromycin phosphotransferase(HPT), as well as genes conferring resistance to herbicidal compounds,such as glyphosate, glufosinate ammonium, bromoxynil, imidazolinones,and 2,4-dichlorophenoxyacetate (2,4-D). See generally, Yarranton (1992)Curr. Opin. Biotech. 3:506-511; Christopherson et al. (1992) Proc. Natl.Acad. Sci. USA 89:6314-6318.

The above list of selectable marker genes is not meant to be limiting.Any selectable marker gene can be used.

A number of promoters can be used in the generation of expressionconstructs. The promoters can be selected based on the desired outcome.That is, the nucleic acids can be combined with constitutive,tissue-preferred, or other promoters for expression in the host cell ofinterest. Such constitutive promoters include, for example, the corepromoter of the Rsyn7 promoter and other constitutive promotersdisclosed in WO 99/43838 and U.S. Pat. No. 6,072,050; the core CaMV 35Spromoter (Odell et al. (1985) Nature 313:810-812); rice actin (McElroyet al. (1990) Plant Cell 2:163-171); ubiquitin (Christensen et al.(1989) Plant Mol. Biol. 12:619-632 and Christensen et al. (1992) PlantMol. Biol. 18:675-689); pEMU (Last et al. (1991) Theor. Appl. Genet.81:581-588); MAS (Velten et al. (1984) EMBO J 3:2723-2730); ALS promoter(U.S. Pat. No. 5,659,026), and the like. Other constitutive promotersinclude, for example, those disclosed in U.S. Pat. Nos. 5,608,149;5,608,144; 5,604,121; 5,569,597; 5,466,785; 5,399,680; 5,268,463;5,608,142; and 6,177,611. These references are incorporated herein byreference.

Further enabled herein is a multigene expression vehicle (MGEV)comprising a polynucleotide having 2 to 8 domain segments, each domainencoding a functional protein wherein at least one domain encodes aClass I defensin and at least one other domain encodes a permeabilizingdefensin, each domain being joined to the next in a linear sequence by alinker sequence encoding a linker, peptide having the amino acidsequence set forth in SEQ ID NO:86.

In an embodiment, at least one other domain encodes a proteinaseinhibitor or a precursor form thereof. As indicated above, the MGEVvector is described in USSN 2007-0277263 which is incorporated herein byreference.

The linker peptide comprises the amino acid sequence X₁X₂X₃X₄X₅ (SEQ IDNO:86) wherein:

-   X₁=E or D-   X₂=E or D-   X₃=K or R-   X₄=K or R-   X₅=N or Q.

The method of transformation/transfection is not critical to the instantdisclosure; various methods of transformation or transfection arecurrently available. As newer methods are available to transform cropsor other host cells they may be directly applied. Accordingly, a widevariety of methods have been developed to insert a DNA sequence into thegenome of a host cell to obtain the transcription and/or translation ofthe sequence to effect phenotypic changes in the organism. Thus, anymethod, which provides for effective transformation/transfection may beemployed.

Transformation protocols as well as protocols for introducing nucleotidesequences into plants may vary depending on the type of plant or plantcell, i.e., monocot or dicot, targeted for transformation. Suitablemethods of introducing nucleotide sequences into plant cells andsubsequent insertion into the plant genome include microinjection(Crossway et al. (1986) Biotechniques 4:320-334), electroporation (Riggset al. (1986) Proc. Natl. Acad. Sci. USA 83:5602-5606,Agrobacterium-mediated transformation. (Townsend et al., U.S. Pat. No.5,563,055; Zhao et al., U.S. Pat. No. 5,981,840), direct gene transfer(Paszkowski et al. (1984) EMBO J. 3:2717-2722), and ballistic particleacceleration (see, for example, Sanford et al., U.S. Pat. No. 4,945,050;Tomes et al., U.S. Pat. No. 5,879,918; Tomes et al., U.S. Pat. No.5,886,244; Bidney et al., U.S. Pat. No. 5,932,782; McCabe et al. (1988)Biotechnology 6:923-926); and Lec1 transformation (WO 00/28058). Alsosee Weising et al. (1988) Ann. Rev. Genet. 22:421-477; Sanford et al.(1987) Particulate Science and Technology 5:27-37 (onion); Christou etal. (1988) Plant Physiol. 87:671-674 (soybean); McCabe et al. (1988)supra (soybean); Finer and McMullen (1991) In Vitro Cell Dev. Biol.27P:175-182 (soybean); Singh et al. (1998) Theor. Appl. Genet.96:319-324 (soybean); Datta et al. (1990) Biotechnology 8:736-740(rice); Klein et al. (1988) Proc. Natl. Acad. Sci. USA 85:4305-4309(maize); Klein et al. (1988) Biotechnology 6:559-563 (maize); Tomes,U.S. Pat. No. 5,240,855; Buising et al. U.S. Pat. Nos. 5,322,783 and5,324,646; Tomes et al. (1995) “Direct DNA Transfer into Intact PlantCells via Microprojectile Bombardment,” in Plant Cell, Tissue, and OrganCulture: Fundamental Methods, ed. Gamborg (Springer-Verlag, Berlin)(maize); Klein et al. (1989) Plant Physiol. 91:440-444 (maize); Fromm etal. (1990) Biotechnology 8:833-839 (maize); Hooykaas-Van Slogteren etal. (1984) Nature (London) 311:763-764; Bowen et al., U.S. Pat. No.5,736,369 (cereals); Bytebier et al. (1987) Proc. Natl. Acad. Sci. USA84:5345-5349 (Liliaceae); De Wet et al. (1985) in The ExperimentalManipulation of Ovule Tissues, ed. Chapman et al. (Longman, N.Y.), pp.197-209 (pollen); Kaeppler et al. (1990) Plant Cell Reports 9:415-418and Kaeppler et al. (1992) Theor. Appl. Genet. 84:560-566(whisker-mediated transformation); D'Halluin et al. (1992) Plant Cell4:1495-1505 (electroporation); Li et al. (1993) Plant Cell Reports12:250-255 and Christou and Ford (1995) Annals of Botany 75:407-413(rice); Ishida et al. (1996) Nature Biotechnology 14:745-750 (maize viaAgrobacterium tumefaciens). These references are incorporated herein byreference, together with USSN 2010-0095408.

Purified defensin proteins can, if desired, be used or optionallycombined with a proteinase inhibitor as a mixture, provided they can beformulated together or sequentially by separate application means. In afurther embodiment, a multiplex approach is used where one of thecomponents is engineered to be produced by the plant and the othercomponent is exogenously supplied. These may be liberally applied orused on selected sites such as seed coatings or around the root tissueor surrounding soil.

In an aspect, the present disclosure teaches a method for the protectionof a plant from a disease associated with a fungal pathogen and thatprevention or treatment results in decreased need for pathogenicidetreatment of plants or plant parts, thus lowering costs of material,labor, and environmental pollution, or prolonging shelf-life of products(e.g. fruit, seed, and the like) of such plants. The method requiresgenetically modifying a plant to express a Class I defensin and apermeabilizing defensin or applying these defensins topically. The term“plant” includes whole plants and parts thereof, including, but notlimited to, shoots, vegetative organs/structures (e.g. leaves, stems andtubers), roots, flowers and floral organs/structures (e.g. bracts,sepals, petals, stamens, carpels, anthers and ovules), seed (includingembryo, endosperm, and seed coat) and fruit (the mature ovary), planttissue (e.g. vascular tissue, ground tissue, and the like) and cells(e.g. guard cells, egg cells, and the like), and progeny of same.

Agronomically useful compositions suitable for use in the systemdisclosed herein include compositions wherein the active ingredient(s)are contained in an effective amount to achieve the intended purposesuch compositions include seed coatings. Determination of the effectiveamounts is well within the capability of those skilled in the art,especially in light of the disclosure provided herein.

In addition to the active ingredients, these compositions for use in theantifungal method may contain suitable agronomically acceptable carrierscomprising excipients and auxiliaries which facilitate processing of theactive compounds into preparations which can be used in the field, ingreenhouses or in the laboratory setting.

Antifungal formulations include aqueous solutions of the activecompounds in water-soluble form. Additionally, suspensions of the activecompounds may be prepared as appropriate oily suspensions. Suitablelipophilic solvents or vehicles include fatty oils such as sesame oil,or synthetic fatty acid esters, such as ethyl oleate or triglycerides,or liposomes. Aqueous injection suspensions may contain substances whichincrease the viscosity of the suspension, such as sodium carboxymethylcellulose, sorbitol, or dextran. Optionally, the suspension may alsocontain suitable stabilizers or agents which increase the solubility ofthe compounds to allow for the preparation of highly concentratedsolutions. Further components can include viscosifiers, gels, wettingagents, ultraviolet protectants, among others.

Preparations for surface application can be obtained by combining theactive compounds with solid excipient, optionally grinding a resultingmixture, and processing the mixture of granules, after adding suitableauxiliaries, if desired, to obtain powders for direct application or fordissolution prior to spraying on the plants to be protected. Suitableexcipients are, in particular, fillers such as sugars, includinglactose, sucrose, mannitol, or sorbitol; cellulose or starchpreparations, gelatin, gum tragacanth, methyl cellulose,hydroxypropylmethyl-cellulose, sodium carboxymethylcellulose, and/orpolyvinylpyrrolidone (PVP). If desired, disintegrating agents may beadded, such as the cross-linked polyvinyl pyrrolidone, agar, or alginicacid or a salt thereof such as sodium alginate.

Whilst the instant disclosure is particularly directed toanti-phytopathogenic methods, the multivalent approach may also be usedin human and non-human subjects, including farm animals and domesticanimals. Generally, a topical approach is used in these circumstances.Commonly, the multivalent approach in human and non-human subjectstarget inter alia yeasts such as Candida and Cryptococcus, dermatophytessuch as Trichophyton and other filamentous fungi including Aspergillusspp such as Aspergillus niger.

The present disclosure further teaches the use of a Class I defensin anda permeabilizing defensin and optionally a proteinase inhibitor or afunctional homolog, analog, derivative or variant thereof of any one orall of these components in a human or non-human animal subject or itsprogeny resistant to fungal or insect pathogen infestation.

Further enabled herein is a method for protecting a human or non-humananimal subject from a disease associated with infection by a pathogen,the method comprising providing cells of the place with a Class Idefensin having a mature domain comprising an amino acid sequenceselected from SEQ ID NOs:81, 83, 85, 3, 6, 9, 12, 15, 18, 21, 24, 27,30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66 and 69, apermeabilizing defensin having a mature domain selected from the listingconsisting of NaD1, TPP3, PhD1A, PhD2, NoD173, SEQ ID NOs:3, 6, 12, 21,24, 70, 71 and 72 or a precursor or a functional homolog, analog,derivative or variant thereof of either or both.

Further enabled herein is a method for protecting a human or non-humananimal subject from a disease associated with infection by a pathogen,the method comprising providing cells of the place with a Class Idefensin having a mature domain comprising an amino acid sequenceselected from SEQ ID NOs:81, 83, 85, 3, 6, 9, 12, 15, 18, 21, 24, 27,30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66 and 69, apermeabilizing defensin having a mature domain selected from the listingconsisting of SEQ ID NOs:3, 6, 12, 21, 24, 70, 71 and 72 or a precursoror a functional homolog, analog, derivative or variant thereof of eitheror both.

A topical composition for treating plants and human and non-human animalsubjects is contemplated herein comprising a Class I defensin and apermeabilizing defensin or a precursor or functional homolog, analog,derivative or variant thereof or either or both. Additional excipientsor carriers may also be included.

EXAMPLES

The present invention is further described in the following non-limitingExamples.

Methods,

Purification of Defensins from Pichia pastoris

A single pPINK-defensin P. pastoris PichiaPink (Trademark) strain 1colony was used to inoculate 25 mL of BMG medium (described in theInvitrogen Pichia Expression Manual) in a 250 mL flask and that wasincubated over for 2-3 days in a 30° C. shaking incubator (140 rpm). Theculture was used to inoculate. 200 mL of BMG in a 1 L baffled flaskwhich was placed in a 30° C. shaking incubator (140 rpm) overnight. Thecells were harvested by centrifugation (2,500×g, 10 min, 4° C.) andresuspended into 1 L of BMM medium in a 5 L baffled flask and incubatedin a 28° C. shaking incubator for 3 days. The cultures were induced att=24 and 48 h. The expression medium was separated from cells bycentrifugation (6000 rpm, 20 min). The medium was adjusted to pH 3.0before it was applied to an SP Sepharose column (1 cm×1 cm, AmershamBiosciences) pre-equilibrated with 100 mM potassium phosphate buffer, pH6.0. The column was then washed with 100 mL of 100 mM potassiumphosphate buffer, pH 6.0 and bound protein was eluted in 10×10 mL of 100mM potassium phosphate buffer containing 500 mM NaCl. Eluted proteinswere concentrated down to 1 mL using a centrifugal column and washed 5×using sterile milli Q ultrapure water. The protein concentration ofPichia-expressed defensin was determined using the bicinchoninic acid(BCA) protein assay (Pierce Chemical Co.) with bovine serum albumin(BSA) as the protein standard.

Analysis of Antifungal Activity of Defensins

The inhibitory effects of each defensin on the growth of Fusariumgraminearum (Giberellazea) (Fgr, Pioneer Hybrid International (PHI)isolate 73B1A), Fusarium oxysporum f. sp. vasinfectum (Fov, Australianisolate VCG01111 isolated from cotton; from Farming Systems Institute,Department of Agriculture, Fisheries & Forestry, Queensland, Australia)or Colletotrichum graminicola (Cgr, PHI isolate Carroll-1A-9),Stenocarpella maydis (DAR51549) (NSW Department of Primary IndustriesAgricultural Scientific Collections Trust (ASCU) or Aspergillus niger(from School of Molecular and Microbial Biosciences, University ofSydney, NSW, Australia) was measured essentially as described byBroekaert et al. (1990) FEMS Microbiol Lett 69:55-59.

Spores were isolated from sporulating fungus spp. growing on syntheticnutrient poor agar (Fgr), V8 agar (Cgr, Fve), ½ strength potato dextrosebroth agar (Fov, Aspergillus niger), yeast extract peptone dextrose agar(Candida albicans, Cryptococcus gattii) or ½ strength Sabouraud dextroseagar (Trichophyton interdigitale, Trichophyton rubrum). Spores wereremoved from the plates by the addition of ½ strength potato dextrosebroth (PDB). Spore concentrations were measured using a haemocytometer.

10× stock solutions of each defensin were prepared in sterile water. TheTecan liquid handling robot was used to serially dilute each defensinand transfer 20 μl of each concentration in triplicate to a 96 wellmicrotitre plate. Spores were added to each plate, 80 μl 5×10⁴ spores/mlin ½ strength PDB. The plates were incubated at 25° C. (Fgr, Cgr, Fve,Fov, F. solani, S. maydis, Aspergillus niger) or 30° C. (C. albicans, C.gattii, T. interdigitale, T. rubrum). Fungal growth was assayed bymeasuring optical density at 595 nm (A595) using a microtitre platereader (SpectraMax Pro M2; Molecular Devices. Growth was allowed toproceed until the optical density (OD) of the fungus in the absence ofany test defensin reached an OD of 0.2. Each test was performed inquadruplicate.

Permeabilization Assay

Fusarium oxysporum f. sp vasinfectum (Fov) or Fusarium graminearum (Fgr)were grown in half-strength PDB from a starting concentration of 5×10⁴spores/mL for 18 hours at 25° C. Hyphal suspension (90 μL) was thentransferred to 96-well microtitre plates and incubated with SYTOX(Registered Trade Mark) green (0.5 μM) for 10 minutes prior to theaddition of 10 μL of peptide solution to give final proteinconcentration, of 10 μM (Fov) or 5 (Fgr). SYTOX green uptake (indicatingpermeabilization) was quantified by measuring fluorescence using amicrotitre plate reader (SpectraMax M5e; Molecular Devices) withexcitation and emission wavelengths of 488 nm and 538 nm, respectively.Readings were taken every 2 minutes for 2 hours. Example results of apermeabilization assay are shown in FIG. 1 and Table 12a.

A relative permeability index is herein defined wherein the degree ofpermeabilisation of a fungal strain induced by a defined concentrationof a defensin is addressed, relative to a value of 1.0 for NaD1 at thesame concentration.

FIG. 1 illustrates the relative uptake of SYTOX green into Fov hyphaeafter treatment with 10 μM NaD1, HXP4, HXL002, HXL007, HXL008 andDmAMP1. See also Table 12a. The defensins NaD1, HXP4, HXL002, HXL007 andHXL008 were able to permeabilize Fov hyphae while the defensin DmAMP1was not. The relative permeability index of each defensin is presentedin Table 12a. For the purposes of this invention, defensins with arelative permeability index of greater than 0.2 on Fov are consideredpermeabilizing.

FIG. 2 illustrates the relative uptake of SYTOX green into Fgr hyphaeafter treatment with 5 μM NaD1, HXP4, HXL001, HXL002, HXL004, HXL008,HXL009, HXL013, HXL021, Hordothionin and RsAFP2. The defensins NaD1,HXP4, HXL002, HXL004 and HXL008 caused significantly morepermeabilisation of Fgr hyphae than the defensins HXL009, HXL021,hordothionin and RsAFP2. The relative permeability index of eachdefensin is presented in Table 12b. For the purposes of this invention,defensins with a relative permeability index of greater than 0.5 on Fgrare considered permeabilizing.

Production of Transgenic Plant Cells and/or Tissue

Techniques and agents for introducing and selecting for the presence ofheterologous DNA in plant cells and/or tissue are well-known. Geneticmarkers allowing for the selection of heterologous DNA in plant cellsare well-known, e.g. genes carrying resistance to an antibiotic such askanamycin, hygromycin, gentamicin, or bleomycin. The marker allows forselection of successfully transformed plant cells growing in the mediumcontaining the appropriate antibiotic because they will carry thecorresponding resistance gene. In most cases the heterologous DNA whichis inserted into plant cells contains a gene which encodes a selectablemarker such as an antibiotic resistance marker, but this is notmandatory. An exemplary drug resistance marker is the gene whoseexpression results in kanamycin resistance, i.e. the chimeric genecontaining nopaline synthetase promoter, Tn5 neomycin phosphotransferaseII and nopaline synthetase 3′ non-translated region described by Rogerset al. (1988) Methods for Plant Molecular Biology.

Techniques for genetically engineering plant cells and/or tissue with anexpression cassette comprising an inducible promoter or chimericpromoter fused to a heterologous coding sequence and a transcriptiontermination sequence are to be introduced into the plant cell or tissueby Agrobacterium-mediated transformation, electroporation,microinjection, particle bombardment or other techniques known to theart. The expression cassette advantageously further contains a markerallowing selection of the heterologous DNA in the plant cell, e.g. agene carrying resistance to an antibiotic such as kanamycin, hygromycin,gentamicin, or bleomycin.

A DNA construct carrying a plant-expressible gene or other DNA ofinterest can be inserted into the genome of a plant by any suitablemethod. Such methods may involve, for example, the use of liposomes,electroporation, diffusion, particle bombardment, microinjection, genegun, chemicals that increase free DNA uptake, e.g. calcium phosphatecoprecipitation, viral vectors, and other techniques practiced in theart. Suitable plant transformation vectors include those derived from aTi plasmid of Agrobacterium tumefaciens, such as those disclosed byHerrera-Estrella et al. (1983) EMBO J 2:987-995; Bevan et al. (1983)Nucleic Acids Res 11(2):369-385; Klee et al. (1985) Bio/Technology3:637-642 and EPO publication 120,516 (Schilperoort et al, EuropeanPatent Publication 120, 516). In addition to plant transformationvectors derived from the Ti or root-inducing (Ri) plasmids ofAgrobacterium, alternative methods can be used to insert the DNAconstructs of this invention into plant cells.

The choice of vector in which the DNA of interest is operatively linkeddepends directly, as is well known in the art, on the functionalproperties desired, e.g. replication, protein expression, and the hostcell to be transformed, these being limitations inherent in the art ofconstructing recombinant DNA molecules. The vector desirably includes aprokaryotic replicon, i.e. a DNA sequence having the ability to directautonomous replication and maintenance of the recombinant DNA moleculeextra-chromosomally when introduced into a prokaryotic host cell, suchas a bacterial host cell. Such replicons are well known in the art. Inaddition, preferred embodiments that include a prokaryotic replicon alsoinclude a gene whose expression confers a selective advantage, such as adrug resistance, to the bacterial host cell when introduced into thosetransformed cells. Typical bacterial drug resistance genes are thosethat confer resistance to ampicillin or tetracycline, among otherselective agents. The neomycin phosphotransferase gene has the advantagethat it is expressed in eukaryotic as well as prokaryotic cells.

Those vectors that include a prokaryotic replicon also typically includeconvenient restriction sites for insertion of a recombinant DNA moleculeof the present invention. Typical of such vector plasmids are pUC8,pUC9, pBR322, and pBR329 available from BioRad Laboratories (Richmond,Calif.) and pPL, pK and K223 available from Pharmacia (Piscataway,N.J.), and pBLUESCRIPT tmand pBS available from Stratagene (La Jolla,Calif.). A vector of the present invention may also be a Lambda phagevector as known in the art or a Lambda ZAP vector (available fromStratagene La Jolla, Calif.). Another vector includes, for example, pCMU(Nilsson et al. (1989) Cell 58:707). Other appropriate vectors may alsobe synthesized, according to known methods; for example, vectors pCMU/Kband pCMUII used in various applications herein are modifications ofpCMUIV (Nilsson et al. (1989) supra).

Typical expression vectors capable of expressing a recombinant nucleicacid sequence in plant cells and capable of directing stable integrationwithin the host plant cell include vectors derived from thetumor-inducing (Ti) plasmid of Agrobacterium tumefaciens.

A transgenic plant can be produced by any standard means known to theart, including but not limited to Agrobacterium tumefaciens-mediated DNAtransfer, preferably with a disarmed T-DNA vector, electroporation,direct DNA transfer, and particle bombardment. Techniques are well-knownto the art for the introduction of DNA into monocots as well as dicots,as are the techniques for culturing such plant tissues and regeneratingthose tissues.

Synergy Classification

Synergy is classified as the difference between the observed % fungalgrowth inhibition caused by the combination of two defensins (Io value)and the expected % fungal growth inhibition of the two defensins basedon the sum of the % fungal growth inhibition of each defensin on its own(Ee value calculated according to the Limpel formula used by Richer etal. (1987) supra). The difference, Io-Ee, is the synergy value. Asynergy value up to 15 means no significant synergy; 15-30 is a lowlevel of synergy; 30-60 is a medium level of synergy; and >60 is a highlevel of synergy.

Bioassay Method for In Planta Studies

Preparation of C. graminicola Inoculum

Colletotrichum graminicola (US isolate Carroll-1A-99) is isolated fromZea maize (Pioneer Hi-Bred International, Inc. Johnston, Iowa, USA).Spores are isolated from sporulating cultures grown on V8 agar forapproximately 2-3 Weeks. C. graminicola spores are collected by scrapingthe surface of the plates in sterile water and separating spores fromhyphal matter by filtration through facial tissue. The concentration ofspores in the filtrate is measured using a haemocytometer.

Preparation of F. graminearum Inoculum

Fusarium graminearum isolate (73B1A) is isolated from Zea maize (PioneerHi-Bred International, Inc. Johnston, Iowa, USA). Spores are isolatedfrom sporulating cultures grown on SNP agar for approximately 2-3 Weeks.F. graminearum spores are collected by scraping the surface of theplates in sterile water. The concentration of spores is measured using ahaemocytometer.

Inoculation of Maize Plants

Plants for bioassay are grown in the glasshouse for approximately 8-10weeks after deflasking.

C. Gramincola Inoculation

Two wounds, 2.0 mm in length are made on opposing sides of the maizeleaf sheath and then overlaid with 1×10⁶ C. graminicola spores/mL.Wounds are then sealed with Glad Press'n'Seal for three days. The areaof infection is measured by digital photography 10 days postinoculation.

F. graminearum Inoculation

Two wounds, 2.0 mm in length are made on opposing sides of the maizeleaf sheath. Wounds are overlaid 6 mm diameter paper discs dipped in1×10⁶ F. graminearums pores/mL. Wounds are then sealed with GladPress'n'Seal for three days. The area of infection is measured bydigital photography 10 days post inoculation.

Analysis of Transgene Expression in Corn Plants

ELISA Method

Protein extract: leaf sheaths are excised from plants grown in theglasshouse. The tissue (50 mg) is frozen in liquid nitrogen and groundin a mixer mill (Retsch MM300) for 2×15 seconds at frequency 30 s⁻¹.Protein extracts are made by adding 450 μL 2% insoluble PVPP(Polyclar)/PBS/0.05% v/v Tween 20 and vortexing for 20 seconds. Thesamples are centrifuged for 10 minutes and the supernatant is collected.

ELISA plates (NuncMaxisorp #442404) are incubated with 100 μL/well ofprimary antibody in PBS (100 ng/well of anti-defensin antibody). Platesare incubated overnight at 4° C. in a humid box. They are then washedfor 2 minutes×4 with PBS/0.05% v/v Tween 20. Plates are blocked with 200μL/well 3% w/v BSA (Sigma A-7030: 98% ELISA grade) in PBS and incubatedfor 2 hours at 25° C. Plates are then washed for 2 minutes×4 withPBS/0.05% v/v Tween 20.

Corn sheath protein extracts (100 μL/well diluted in PBS/0.05% v/v Tween20) are then applied to the plates which are then incubated for 2 hoursat 25° C. Plates are then washed for 2 minutes×4 with PBS/0.05% v/vTween 20 and then 100 μL/well of secondary antibody in PBS (e.g. 75ng/well biotin-labeled defensin antibody) is applied. The biotin labeledantibody is prepared using the EZ-link Sulfo-NHS-LC-biotinylation kit(Pierce); 2 mL of protein A purified antibody and 2 mg of the biotinreagent are used. Plates are incubated for 1 hour at 25° C. and thenwashed for 2 minutes×4 with PBS/0.05% v/v Tween 20 and 100 μL/well ofNeutriAvidin HRP-conjugate (Pierce #31001; 1:1000 dilution; 0.1 μL/well)in PBS is applied. The plates are incubated for 1 hour at 25° C. andthen washed for 2 minutes×2 with PBS/0.05% v/v Tween 20, followed by 2minutes×2 with H₂O. Just before use, the substrate is prepared bydissolving 1 ImmunoPure OPD tablet (Pierce #34006) in 9 mL H₂O, thenadding 1 mL stable peroxide buffer (10×, Pierce #34062). The substrateis applied at 100 μL/well and plates are incubated at 25° C. until colordevelops. The reaction is stopped by applying 50 μL 2.5 M sulfuric acid.Absorbance at 490 nm is measured in a plate reader (Molecular Devices).

Example 1 Inhibition of the Growth of Fungal Pathogens in, the Presenceof a Permeabilizing Defensin and a Class I Defensin In Vitro

The inhibitory effects of a permeabilizing defensin in combination witha Class I defensin on the growth of Fusarium graminearum (Giberellazea)(Fgr, Pioneer Hybrid International (PHI) isolate 73B1A), Fusariumoxysporum f. sp. vasinfectum (Fov, Australian isolate VCG01111 isolatedfrom cotton; from Farming Systems Institute, Department of Agriculture,Fisheries & Forestry, Queensland, Australia), Fusarium solani (fromSchool of Botany, University of Melbourne, Victoria, Australia),Colletotrichum graminicola (Cgr, PHI isolate Carroll-1A-9),Stenocarpella maydis (DAR51549) (NSW Department of Primary IndustriesAgricultural Scientific Collections Trust (ASCU) Aspergillus niger (fromSchool of Molecular and Microbial Biosciences, University of Sydney,NSW, Australia), Candida albicans (isolate DAY185, Department ofBiochemistry and Molecular Biology, Monash University, Victoria,Australia), Cryptococcus gattii (isolate BAL11), Trychophytoninterdigitale or Trychophyton rubrum (both obtained from the NationalMycology. Reference Centre, South Australia Pathology at the Women's andChildren's Hospital, Adelaide, Australia) was measured essentially asdescribed by Broekaert et al. (1990) supra.

Spores were isolated from sporulating fungus spp. growing on syntheticnutrient poor agar (Fgr), V8 agar (Cgr), ½ strength potato dextrosebroth agar (Fov. Aspergillus niger), yeast extract peptone dextrose agar(Candida albicans, Cryptococcus gattii) or ½ strength Sabouraud dextroseagar (Trichophyton interdigitale, Trichophyton rubrum). Spores wereremoved from the plates by the addition of ½ strength potato dextrosebroth (PDB). Spore concentrations were measured using a haemocytometer.

Antifungal assays were conducted in 96 well microtitre platesessentially as described in the detailed description (Analysis ofantifungal activity of defensins). Wells were loaded with 10 μL offilter sterilized (0.22 μm syringe filter, Millipore) defensin 1 (10×stock for each final concentration) or water, 10 μL of filter sterilized(0.22 μm syringe filter, Millipore) defensin 2 (10× stock for each finalconcentration) or water and 80 μL of 5×10⁴ spores/mL in ½ strength PDB.The plates were incubated at 25° C. (Fgr, Cgr, Fov, F. solani, S.maydis, Aspergillus niger) or 30° C. (C. albicans, C. gattii, T.interdigitale, T. rubrum). Fungal growth was assayed by measuringoptical density at 595 nm (A595) using a microtitre plate reader(SpectraMax Pro M2; Molecular Devices. Growth was allowed to proceeduntil the optical density (OD) of the fungus in the absence of any testdefensin reached an OD of 0.2. Each test was performed in duplicate.

Synergy is classified as the difference between the observed % fungalgrowth inhibition caused by the combination of two defensins (Io value)and the expected % fungal growth inhibition of the two defensins basedon the sum of the % fungal growth inhibition of each defensin on its own(Ee value calculated according to the Limpel formula used by Richer etal. (1987) supra). The difference, Io-Ee, is the synergy value. Asynergy value up to 15 means no significant synergy; 15-30 is a lowlevel of synergy; 30-60 is a medium level of synergy; and >60 is a highlevel of synergy. Synergy calculations are presented in Tables 3 through11 wherein, as indicated above, Ee is the expected effect from theadditive response according to Limpel's formula expressed as percentinhibition and Io is the percent inhibition observed. Synergy occurswhen Io values are higher than Ee values.

Results

The results are shown in Tables 3 through 11.

Example 2 In Planta Synergy of IMP 4 with SBI6 Against Fusariumgraminearum and Colletotrichum graminicola

Transgenic corn plants are produced by Agrobacterium-mediatedtransformation or particle bombardment using standard protocols such asthose described in U.S. Pat. No. 5,981,840; U.S. Pat. No. 7,528,293;U.S. Pat. No. 7,589,176; U.S. Pat. No. 7,785,828; Frame et al. (2002)Plant Physiology 129:13-22. A binary vector containing GAT as theselectable marker, a ubiquitin promoter for constitutive expression anda codon optimized sequence encoding either HXP4, SBI6 or HXP4+SBI6 (viaa double expression vector) is transferred into an Agrobacteriumtumefaciens strain by electroporation. Immature corn embryos areinfected via immersion in a suspension of Agrobacterium followed by aperiod of co-culture on a solid medium. The embryos are then optionally“rested” during which time they are incubated in the presence of atleast one antibiotic which inhibits the growth of Agrobacterium. Next,transformed callus is obtained by culturing the infected embryos onsolid medium containing glyphosphate which inhibits the growth ofnon-transformed cells. Transformed callus is then able to be regeneratedinto plants using standard methods. Plants expressing both HXP4 and SBI6may also be generated via a cross of individual events.

Levels of HXP4 and SBI6 expression in PCR positive plants aredetermined, for example, by ELISA screening (see Methods). Plantsexpressing HXP4>10 ppm and/or SBI6 at >0.9 ppm are assessed forincreased resistance to Fusarium graminearum and Colletotrichumgraminicola using the bioassay described in the Methods.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications. The invention alsoincludes all of the steps, features, compositions and compounds referredto or indicated in this specification, individually or collectively, andany and all combinations of any two or more of said steps or features.

TABLE 3 Fusarium graminearum Permeabilizing Expected Observed defensinClass I defensin inhibition inhibition Synergy NaD1 (0.5 μM)Hordothionin (2 μM) 26.3 93 66.7 Zeathionin-2 (2 μM) 36.3 86.2 49.9 PsD1(2 μM) 0 75.5 75.5 HXL004 (2 μM) 18.6 70.5 51.9 HXL001 (0.5 μM) 54.0100.0 46.0 SBI6 (2 μM) 0 80.3 80.3 HXL008 (0.5 μM) 0 91.5 91.5 HXL009 (1μM) 0 72.3 72.3 HXL012 (1 μM) 16.7 93.4 76.7 HXL015 (0.25 μm) 0 44.744.7 HXL021 (0.3 μM) 4.9 70.4 65.5 RsAFP2 (0.125 μM) 21.5 67.2 45.7HXL002 (0.5 μM) 39.2 93.3 54.0 NaD1 (0.25 μM) SBI6 (0.5 μM) 21.5 52.130.5 HXP4 (0.125 μM) Hordothionin (1 μM) 18.4 90.3 71.9 Zeathionin-2 (1μM) 12.7 85.4 72.7 SBI6 (2 μM) 22.5 87.2 64.7 VP45 (0.5 μM) 11.2 93.382.1 SBI6 (1 μM) 19.3 90.8 71.5 HXL008 (0.25 μM) 34.5 97.8 63.3 HXL009(0.25 μM) 33.4 93.1 59.7 HXL012 (0.25 μM) 49.6 92.5 42.9 HXL015 (0.125μm) 41.9 91.3 49.4 HXL021 (0.125 μM) 38.8 90.4 51.6 RsAFP2 (0.125 μM)58.8 89.9 31.1 HXP4 (0.125 μM) HXL012 (0.5 μM) 8.4 80.7 72.3 HXL015 (1μM) 17 94.2 77.2 TPP3 (0.2 μM) Hordothionin (1 μM) 5.9 85.9 80 PHI-004(2 μM) 0 67 67 SBI6 (1 μM) 16.2 68.6 52.4 HXL001 (0.5 μM) Hordothionin(4 μM) 17.7 78.9 61.2 HXL004 (4 μM) 6.1 69.4 63.3 HXL010 (4 μM) 14.2 6045.8 Zeathionin-2 (4 μM) 3.2 43.2 40 HXL001 (1 μM) HXL015 (0.5 μM) 1093.9 83.9 HXL021 (0.25 μM) 7.6 91.5 83.9 HXL007 (0.5 μM) Hordothionin (4μM) 20.8 74.3 53.5 HXL004 (4 μM) 4.9 67.2 62.3 HXL010 (4 μM) 12.7 62.249.5 Zeathionin-2 (4 μM) 9.9 54.4 44.5 HXL008 (0.5 μM) Hordothionin (4μM) 14.9 74.6 59.7 HXL004 (0.5 μM) HXL012 (1 μM) 0 55.2 55.2 HXL015 (1μM) 12 98.3 86.3 HXL008 (0.5 μM) 28.2 73.6 45.4 HXL009 (2 μM) 37.8 60.222.4 SBI6 (4 μM) 4.1 82.5 78.4

TABLE 4 Colletotrichum graminicola Permeabilizing Expected Observed Syn-defensin Class I defensin inhibition inhibition ergy NaD1 (1.25 μM) SBI6(0.5 μM) 24.7 92.1 67.4 HXL008 (2 μM) 14.3 46.3 32.0 NaD1 (5 μM)Hordothionin (4 μM) 0 80.6 80.6 Zeathionin-2 (4 μM) 19.5 81.6 62.1DmAMP1 (2 μM) 13.9 61.1 47.2 HXP4 (1.25 μM) HXL008 (2 μM) 19.9 77.0 57.1HXL009 (2 μM) 9.5 38.3 28.8 HXP4 (2.5 μM) Hordothionin (2 μM) 11.3 41.930.6 Zeathionin-2 (2 μM) 8.4 21.1 12.7 SBI6 (2 μM) 22.5 87.2 64.7 PsD1(4 μM) 29.9 50.9 21 PhD2 (5 μM) Hordothionin (2 μM) 42.2 70.8 28.6Zeathionin-2 (2 μM) 35.5 55.5 20 TPP3 (2 μM) Hordothionin (1 μM) 0 86.386.3 HXL004 (4 μM) 6.9 51.9 45 SBI6 (1 μM) 0 28.7 28.7 HXL008 (2.5 μM)Hordothionin (2 μM) 6.3 95.4 89.1 HXL004 (4 μM) 0 76.4 76.4 HXL010 (4μM) 13 46.6 33.6 Zeathionin-2 (4 μM) 1.5 29.7 28.2 HXL001 (2.5 μM)Hordothionin (2 μM) 0 59.8 59.8 HXL004 (4 μM) 2.6 44.7 42.1 HXL002 (2.5μM) HXL008 (4 μM) 20.9 84.6 63.7 HXL012 (1 μM) 39.4 86.4 47 SBI6 (4 MM)43.5 84.8 41.3 RsAFP2 (4 μM) 8.4 57.9 49.5 HXL004 (1.25 μM) Hordothionin(2 μM) 21 57.6 36.6 RsAFP2 (4 μM) 20.9 66.9 46 HXL008 (1 μM) 26.5 87.861.3 HXL012 (1 μM) 30.7 79.7 49 SBI6 (2 μM) 10.1 55.3 45.2 HXL015 (2 μM)44.5 80.1 35.6

TABLE 5 Fusarium solani Permeabilizing Expected Observed defensin ClassI defensin inhibition inhibition Synergy HXP4 (0.125 μM) SBI6 (2 μM) 081.4 81.4

TABLE 6 Aspergillus niger Permeabilizing Expected Observed defensinClass I defensin inhibition inhibition Synergy NaD1 (3 μM) SBI6 (2 μM)31.9 93.8 61.9

TABLE 7 Stenocarpella maydis Permeabilizing Expected Observed defensinClass I defensin inhibition inhibition Synergy HXP4 (1.25 μM) SBI6 (2μM) 44.2 78.9 34.7

TABLE 8 Candida albicans Permeabilizing Expected Observed defensin ClassI defensin inhibition inhibition Synergy NaD1 (4 μM) HXL008 (4 μM) 4395.3 52.3 HXL009 (4 μM) 46 97.6 51.6 SBI6 (1 μM) 18.4 93 74.6 HXL021 (4μM) 24.3 87.6 63.3 NaD1 (2 μM) HXL012 (1 μM) 26.4 94.3 67.9 HXL015 (2μM) 11.9 99.3 87.4 Hordothionin (4 μM) 0.7 87.9 87.2 RsAFP2 (4 μM) 12.243.6 31.4 HXP4 (2 μM) HXL008 (4 μM) 23.4 100 76.6 HXL009 (4 μM) 0 83.483.4 HXL012 (0.5 μM) 0 98.6 98.6 SBI6 (2 μM) 0 96.5 96.5 HXL015 (1 μM)7.8 98.8 91 Hordothionin (2 μM) 13.2 91 77.8 RsAFP2 (4 μM) 38.1 74.836.7 HXL021 (4 μM) 0 76.5 76.5 HXL001 (4 μM) HXL008 (4 μM) 16.3 92.876.5 HXL009 (4 μM) 20.7 51.2 30.5 HXL012 (1 μM) 15.5 94.4 78.9 SBI6 (2μM) 35.8 97.6 61.8 HXL015 (2 μM) 50.2 100 49.8 Hordothionin (2 μM) 23.982.7 58.8 RsAFP2 (4 μM) 34.5 95.5 61 HXL021 (4 μM) 34.6 87.9 53.3 HXL002(4 μM) HXL008 (4 μM) 6.5 93 86.5 HXL012 (1 μM) 26.4 100 73.6 SBI6 (2 μM)48.2 86 37.8 HXL015 (2 μM) 18.6 100 81.4 Hordothionin (2 μM) 7.3 80 72.7RsAFP2 (4 μM) 11.8 87.8 76 HXL021 (4 μM) 15.4 79.3 63.9 HXL004 (2 μM)HXL008 (4 μM) 24 87.2 63.2 HXL012 (1 μM) 1 85.4 84.4 SBI6 (2 μM) 0 79.679.6 HXL015 (2 μM) 20.1 90 69.9 Hordothionin (4 μM) 3.3 89.7 86.4 RsAFP2(4 μM) 23 87.6 64.6 HXL021 (4 μM) 0 82.2 82.2

TABLE 9 Cryptococcus gattii Permeabilizing Expected Observed defensinClass I defensin inhibition inhibition Synergy NaD1 (1 μM) HXL008 (2 μM)52.8 100 47.2 HXL009 (2 μM) 47.4 99.5 52.1 HXL012 (1 μM) 34.7 99.3 64.6SBI6 (2 μM) 6.5 88.8 82.3 HXL015 (1 μM) 41.8 75.5 67.9 Hordothionin (4μM) 66.4 88.2 21.8 HXP4 (0.5 μM) HXL008 (1 μM) 47.7 99 51.3 HXL009 (1μM) 49.4 100 50.6 HXL012 (0.5 μM) 26.3 99 72.7 SBI6 (2 μM) 34.2 95.2 61Hordothionin (2 μM) 23.8 69.4 45.6 RsAFP2 (4 μM) 53.8 100 46.2 HXL001 (1μM) HXL012 (1 μM) 15.8 95.8 80 HXL002 (1 μM) HXL008 (4 μM) 8.6 100 91.4HXL009 (2 μM) 29.9 84.6 54.7 HXL012 (1 μM) 23.1 100 76.9 SBI6 (2 μM)18.8 91.9 73.1 HXL015 (1 μM) 0 100 100 Hordothionin (2 μM) 12.4 97.785.3 RsAFP2 (4 μM) 26.3 85.2 58.9 HXL021 (2 μM) 29.2 58 28.8 HXL004 (1μM) HXL008 (2 μM) 0.5 71 70.5 HXL012 (1 μM) 26.5 97.3 70.8 SBI6 (2 μM)33 87 54 HXL015 (1 μM) 0 99 99 Hordothionin (2 μM) 8 62.9 54.9 HXL021 (2μM) 11.1 90.5 79.4

TABLE 10 Trichophyton interdigitale Permeabilising Expected Observeddefensin Class I defensin inhibition inhibition Synergy HXP4 (0.5 μM)Hordothionin (2 μM) 51.9 87.1 35.2 HXL008 (0.25 μM) 34.7 67.7 33.0 NaD1(0.5 μM) Hordothionin (1 μM) 9.8 33.7 23.9 HXL009 (0.5 μM) 28 61.2 33.2HXL008 (0.25 μM) 29.7 72.6 42.9 HXL004(1 μM) 22.2 56.2 34.0 HXL001 (0.5μM) RsAFP2 (0.5 μM) 5.9 30.6 24.7 Hordothionin(2 μM) 48 76.5 28.5 HXL001(1 μM) HXL008(0.25 μM) 10.6 51.6 41.0 HXL002 (0.5 μM) Hordothionin(2 μM)50.2 85.3 35.1 HXL008(0.25 μM) 27.7 69.7 42.0 HXL004 (1 μM)Hordothionin(2 μM) 57.5 93.6 36.1 HXL008(0.25 μM) 23.0 70.4 47.4

TABLE 11 Trichophytonrubrum Permeabilizing Expected Observed defensinClass I defensin inhibition inhibition Synergy NaD1 (1 μM) HXL009 (2 μM)50.8 70.2 19.4 HXL004 (1 μM) HXL008 (0.25 μM) 18.3 51.7 33.4

TABLE 12a Permeability Defensin index HXL007 1.2 350 NaD1 1.0 300 HXL0020.9 260 HXL008 0.8 225 HXP4 0.7 220 DmAMP1 0.0 0

TABLE 12b Permeability Defensin index HXL004 1.6 500 HXL013 1.4 450 HXP41.3 400 NaD1 1.0 320 HXL002 1.0 320 HXL001 0.9 300 HXL008 0.9 300 HXL0210.5 150 HXL009 0.4 120 Hordothionin 0.4 120 RsAFP2 0.3 100

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The invention claimed is:
 1. A method for treating fungal pathogeninfection of a subject, said method comprising providing cells of saidsubject with a Class I defensin, wherein the Class I defensin has amature domain comprising an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 85, 3, 6, 12, 24, 27, 36, 39 and 45, and apermeabilizing defensin having a mature domain selected from the groupconsisting of NaDI, TPP3, PhD1A, PhD2, NoD173, SEQ ID NOs: 3, 6, 12, 24,70, 71 and 72, wherein the Class I defensin and the permeabilizingdefensin are not the same.
 2. The method of claim 1, wherein the subjectis a plant.
 3. The method of claim 2, wherein the Class I defensin andpermeabilizing defensin are produced by a genetically modified plantcell or both defensins are applied topically to the plant or via theplant's root system or as a seed coating or as a surface spray.
 4. Themethod of claim 1, further comprising providing the cell of said subjectwith a proteinase inhibitor or precursor form thereof.
 5. The method ofclaim 1, wherein the fungal pathogen is selected from the groupconsisting of Fusarium graminearum, Colletotrichum graminicola,Leptosphaeria maculans, Alternaria brassicicola, Alternaria alternata,Aspergillus nidulans, Botrytis cinerea, Cercospora beticola, Cercosporazeae maydis, Cochliobolus heterostrophus, Exserohilum turcicum, Fusariumculmorum, Fusarium oxysporum, Fusarium solani, Fusariumpseudograminearum, Fusarium verticilloides, Gaeumannomyces graminis var.tritici, Plasmodiophora brassicae, Sclerotinia sclerotiorum,Stenocarpella maydis, Thielaviopsis basicola, Verticillium dahliae,Ustilago zeae, Puccinia sorghi, Macrophomina phaseolina, Phialophoragregata, Diaporthe phaseolorum, Cercospora sojina, Phytophthora sojae,Rhizoctonia solani, Phakopsora pachyrhizi, Alternaria macrospora,Cercospora gossypina, Phoma exigua, Puccinia schedonnardii, Pucciniacacabata, Phymatotrichopsis omnivora, Fusarium avenaceum, Alternariabrassicae, Alternaria raphani, Erysiphe graminis, Septoria tritici,Septoria nodorum, Mycosphaerella zeae, Rhizoctonia cerealis, Ustilagotritici, Puccinia graminis, Puccinia triticina, Tilletia indica,Tilletia caries, and Tilletia controversa, Aspergillus niger, Candida,Cryptococcus, Trichophyton interdigitale and Trichophyton rubrum.
 6. Themethod of claim 2, wherein the plant is a crop plant selected from thegroup consisting of a forage crop, oilseed crop, grain crop, fruit crop,vegetable crop, fiber crop, spice crop, nut crop, turf crop, sugar crop,beverage crop and a forest crop.
 7. The method of claim 6, wherein thecrop plant is selected from the group consisting of soybean, canola,corn, cotton and wheat.
 8. The method of claim 2, wherein the Class Idefensin and permeabilizing defensin are applied as a seed coating. 9.The method of claim 1, wherein the subject is a human or non-humananimal.
 10. The method of claim 9, wherein the Class I defensin andpermeabilizing defensin are applied topically to the human or non-humansubject.
 11. The method of claim 1, wherein the Class I defensin has amature domain selected from the group consisting of SEQ ID NOs:6, 12,24, 27, 36 and 45, and the permeabilizing defensin has a mature domaincomprising an amino acid sequence selected from the group consisting ofSEQ ID NOs:6, 12, 24 and
 70. 12. The method of claim 4, wherein theproteinase inhibitor is a cystatin.
 13. The method of claim 5, whereinthe Fusarium oxysporum is selected from the group consisting of Fusariumoxysporum f. sp. vasinfectum, Fusarium oxysporum f. sp. dianthi andFusarium oxysporum f. sp. lycopersici.